I have posted about this before but more in relation to maintenance.
So I used to have DC every Friday. One week I'd take them to ex on Saturday morning, the next week on Sunday morning. They always come back to me Tuesday after school.
This way we both got a bit of time with DC at weekends.
6 weeks ago Ex asked if we could change it so the weekend he has DC from Saturday, he would have them from Friday instead.
In hindsight I feel as this is so he could pay less maintenance.
I now only get to spend weekend time with my DC once a fortnight whereas he sees them every weekend. I do the lions share of shit school run bits.
Aibu? When questioned he said oh well we'll ask DC what they want to do, knowing full well they'll want to be with dad and their iPads, sweets and slack parenting.