AIBU to give my 6-year-old 45 minutes in her room?

So she can be angry. Removing a treat later in the day is perfectly fine. Actions have consequences, that's real life.

I think it is a bit long but I can see how you got there and it’s not terrible. Does she respond to praise/rewards for good behaviour?

I don't think it's too long, sometimes a reset is needed. And at that age they really need to know that the boundaries are firm and that what you say will actually happen. Sounds like it's not a regular occurrence for her to push it this far, and that it usually works as a behavioural management strategy.

I would say that if this does happen a few times and behaviour isn't changing perhaps it's no longer an effective strategy and you might need a new system.

Super nanny is a women who has never raised her own kids. Most of the people she visited had fucked up families and anyone with half a brain cell could offer advice. I cringed when I saw her programs.

The naughty step is hideous

Well as a punishment/deterrent it’s not very effective if she managed to escalate from 5 minutes to 45. How many times did she push back to get to that point? She’s 6 years old, at that age mine were told very clearly to pack it in, and physically removed from the situation if need be. She’d have found herself folding laundry and dusting in my house - busy work alongside me rather than chilling in her room.

I say kindly & without judgement, as 6 years old comes with very 'big feelings' & it's bloody hard for you especially in the holidays. YABU I do not believe been sent to their bedroom should be used as punishment.
Quite willing to be shot down. As I am long in the tooth & there may be more 'modern' practices that I am unaware of.
The attitude does need to be nipped in the bud. However 6 is also old enough for consequences. 10 minute time out in a boring place, we used to use the hallway, bottom step. I would say is max, or until the wailing stops. then an apology for the behaviour. Removal of privileges- screen time for that day etc etc. We always started afresh the next day, grudges/punishment not carried forward. I always chatted at bedtime, setting up what the next day would bring, what behaviour was expected, if they have been good, wasn't today lovely with us all been nice taking turns etc, or let's try harder tomorrow to be kind as it makes everyone sad when there is shouting & in kindness & then reminded at breakfast, ie ok DC's remember today we are going swimming this afternoon, this morning X is watching the end of his programme, Y you can watch with or play Lego/ colour in or help me in the garden. We are going to have a lovely day.
The absolute trick here is confidence & calmness, which is a feat in itself when you are exhausted & want to go hide under the duvet. Bluff it, until it becomes second nature.

I’m a teacher. It’s often suggested that the language of choice can be more effective, and also giving them a way to back down while saving face. So “You’re choosing to prevent DS from watching his programme, which means that you have to [consequence]. But, if you choose instead to read/help me tidy up/play something while he’s watching his programme, that would mean you could [whatever nice thing] instead of [consequence].”

Maybe while she’s calm you and she could talk about how she’s behaving at the moment and how both of you feel at those times? Kids can be quite astute and aware, it helps to name the feelings, and she might tell you how she’d like you to deal with things. Or at least how she’d expect you to deal with her brother if he were behaving as she is! Doesn’t need to be a shaming conversation, just an open one.

I'd say it depends on whether she will spend the time in her room quietly playing/reading or whether she'll continue the strop and throw all her toys on the floor/strip the covers off her bed and try to fling them out of the window etc.

Hopefully she'll sit and sulk for a few minutes and then start to play. Then I'd go in after about twenty minutes, tell her time was up and carry on with the day.

I never used the kids bedrooms as punishment spaces as their bedroom is supposed to be relaxing and safe - not somewhere to go when being sent away as they have been naughty.

Kids can be arses - I’ve got three.

The increasing the time doesn’t matter when she is in full fuckery mode - time to a six year old means nothing. 5 mins or 50 mins she won’t be able to regulate herself quickly enough to bring herself down before extra time is needed.

6 & 4 year olds are going to be patented differently as their needs are different.

At six I would probably just ignore it then revisit when she’s calmed down and discuss why she acted like that and how it made you feel. six year old girlies are demanding and bossy I’ve had three of them 🫣

She will probably spend ten minutes sulking and then get distracted by a book or a toy and start playing.

She probably won’t do any tidying, if you want the tidying done you will have to go up after about 20 minutes and say “how’s the tidying going, do you need any help”, Or just forget about the tidying and stick with the 45 minutes.

45 mins is too long but her answer of NO when being told to go to her room is not acceptable.

You need to do it supernanny style and take her to her room/time out space for 6 minutes then if she comes back out then take her back. She then needs to apologise when she has served her time.

1 minute per year of their age is appropriate.

Sending a child to their room is ineffective.
One second you are saying go to your room to play/rest/have your own space and the next that room is a punishment zone

Get a naughty step

I feel that regardless of whether 45 minutes is too long, you now need to follow through. Because if you back down, next time your boundary of extended time will have zero effort as she will know that it's an empty threat.
Hopefully, this will only need to happen once.

45 minutes in a low stimulating environment is absolutely fine for the child of this age. Remembering myself at that age, this would actually be more of a reward than punishment (we had a busy household and everyone lived on top of each other so having a room to yourself for the whole 45 minutes would be amazing!)

I don't think it's awful or anything, and I can see why you don't want to back down. But I'm not sure it's the most effective. 45 minutes will feel extremely long to her. Does she have a way of knowing the time? If not I'd go in after 20 minutes and tell her it was 45. It will still feel like a very long time from her point of view.

I just want to add, you sound like a good mum, don't be downhearted. It's the middle of the summer holidays and they're going to be acting up. Sometimes it does feel like you're being harder on one of them, but as long as you try to be fair it'll all turn out ok. This time next year your DD could be an angel and her brother could be the one who's always acting out! Mine used to go through phases.

Have a cup of tea and don't be too hard on yourself. Then get them outdoors and let them run it off!

No, it’s not too much. She’s behaving terribly and needs an appropriate punishment. She needs to learn boundaries and appropriate behaviour. She also needs to learn that you mean what you say, so don’t capitulate on the 45 minutes.

And your son deserves the time you promised him so he could finish watching his programme, without his sister interrupting and complaining!

Sorry but I do think 45 minutes is too long.

Press reset and go up shortly for a chat and focus on positive behaviour rather than negative. Very hard to do when she’s being so difficult.

Also, removing a treat later in the day for rudeness at breakfast time is probably too much as well and likely to reinforce her anger.