I know shared arrangements are popular now, but I'm not convinced they're in the inerest of the child.
A few years ago we had a horrible spell in our county where we had far too many teenagers committing suicide. Schools felt they were facing critism about the pressure children were under/bullying etc and did a piece of work to try and find out what was happening and how these awful deaths could be prevented.
It was only a small sample, although also far too large and research wasn't scientific, but the only things they all, every single one, had in common was that they had previously self harmed (although some a long time ago) and they had homelives where parents had split but both parents were still very much around/shared residency. Not all 50/50, but significant time spent with both parents.
Other than that the children were a real mix of sporty or not, academically gifted, average and struggling, popular and bullied, affluent, average, deprived. We couldn't find anything else in common.
Now obviously lots of children live in these situations without coming to such tragic harm and correlation doesn't equal cause etc, but I really feel strongly that that information is worth further research. People don't want to hear it though, everyone wants to believe "fair" is best, but who's it fair/best for?
I know I'd be unsettled if I was going to a different home on different days and that's without the pull of different parents. I'm sure lots manage to create home where that doesn't happen, but most children must feel it to some extent?