Well, my username was thought up when I was 0.6 and that was really a position where I thought I wasn't giving my DC the best and I also wasn't able to get enough work done.
I do find now I'm 0.8 that it's not too bad, helped by only having DC2 on my day off (and DC2 is young enough to nap).
Like most academics I don't just work 9-5 on my working days - but the non-contracted hours that I work are almost exclusively urgent matters/finishing stuff I'm in the flow of, after the DC have gone to bed. With the age and personality of our DCs I couldn't put in a full day at the weekend even with DH around, except for the occasional open day/travel. It just isn't fair on DH or the DCs.
We now have an email contract between colleagues (don't send outside working hours) and students (they actually pay more attention to me not working certain hours than other colleagues, I find). It's not 100% but it helps.
I do obviously also work on non-contracted days for conferences/travel and either I arrange childcare or DH takes a day off.
However I do not and cannot work on my day off as a regular thing (no email except maybe checking for urgent things I'm waiting for a response to, after bed, I don't set my phone to download that day, and I definitely don't sit at the computer working on a document) because I cannot do that with a DC around. I know some people can - and some people have competitive BF-while-writing or toddler-sick-in-office stories. But my DCs are not old enough to amuse themselves and except for when VERY tiny have never been reliably quiet enough for me to work when they are around.
DH also works PT (he's in a govt job, technical stuff) which helps more now e.g. having one day I don't have to dash for the nursery pickup. I suspect he also wants to carry on PT when DC2 starts school but he wouldn't feel as guilty as me about doing 0.8 and having the morning to himself! Also, his job is a bit more flexible - so if a DC had a hospital appointment he could just say "I'll do the morning of my day off instead" whereas I have (some of you may remember) a really irritating HR/HoD who doesn't like that, plus of course I might already have a lecture that day etc.