Mine varied anywhere from 3yrs up to 5. They always had their own bed available. And the progression wss gradyal so they might start off in their own bed then come through to mine. Eventually they just stopped needing to. There might be the odd night if they were ill.
My youngest sleeps in my room still but he has additional needs. He gas on occasion slept somewhere else and again has a bed in another room if he wants, and am sure he will. Its no hardship to have him in my room tbh.
When they are little they did sleep on, very close to me, as babies do. I would have a carrycot in living room if I needed to put them down safely. Then once old enough to be in a room as owe safe sleep guidelines of 6 months I would stsrt seeing if they would sleep in bed for a few hours without me there. It was always done gradually, thete would be phases when I would havr to stay with them ie illness, teething. And it meant when they woke or stirred in night it was very easy to resettle them. I didnt need to get up. They were comforted. One of my boys would just reach out in his sleep to feel that I was there, his hand touching my skin gave him the reassurance he needed.
I have always been a boring mummy in the night, cuddles, nursing, etc as needed as you do with a baby. But no chatting, chatting playing. To
It was always gradual the stretches of sleep got longer, the awake spells got shorter etc. And as is normal for babies and toddlers it wasnt linear some nights were better than others, there were weeks they needed my presence more but that would be the same if they were in a cot in another room.
We did try a cot with my eldest, 3 years of not getting much sleep at all, despite a routine, all the right things etc. Even trued sleep training and quickly realised it was not going to work as within minutes he could scream himself sick! He just didnt need much sleep. Eventually he had a little set up with his toddler bed, a pile of books by his bed to look at and he would do that til he fell asleep and if he woke. His bedroom eas opposite ours so he could see and cone to us if he needed anything. He still at 26 doesnt need as much sleep as most.
I had number 2 when no 1 was 2, so had to meet both their needs and at that point decided it was far easier to just have baby in with me, so I could feed on demand without getting up. It also meant i could settle him quickly and he wouldnt then wake up number 1!
I ended up tandem feeding no 2 and no 3. The same again with no 3 and no 4.
No 4 weaned before I had 5, and there is a big gap 5 years between no 5 and 6.
Its just what worked. They are 26, 23, 21, 17, 15 and 9 now. One is married. Eldest 3 have all left home, independent and grown.
The teens happily sleep in their own rooms.
But it was done gradually, without training them. And in a way that worked for us and felt right.