Setup matters a lot, eg if you have a separate room to go to or a standalone unit in the back yard.

Kids are "sticky" (once they get into your office for any reason it can be difficult to get them out again).

Number of kids matters, their ages matter, their needs matter, sometimes they "get loose" while carer is busy with one (e.g. putting to sleep), and carers need breaks too.

For my particular situation, I can get noticeably more done on days when all the kids are out, even when someone else is ostensibly caring for them "full time".