When me and x-h split (it took him 9 months to actually move), he moved out on the Monday and saw the children on Wednesday night (at my house) and had them overnight at his new lodgings on the Friday night.
7 years on - he no longer comes to my house on a Wednesday - this died off because he lives 1 hour drive away and by the time he got here, it was time for the younger 2 to go to bed.
He still has them as follows:-
One night a week, every week - normally Friday but can be changed to Saturday if either him or I have made plans on that day
One week at Easter - either leading up to Good Friday or the week after Easter Monday (different last year because of school holidays falling later than Easter holidays).
Two weeks in the summer holidays.
If I need/want/like to go away for the weekend, he will have them both nights - on the other hand, probably once/twice a year, he does not have them at all because of weekends away, etc. but he will then have them two nights the following weekend.
When he first left, the children were less than 1 year, 4 years and 8 years. Now they are 16, (nearly) 12 and 7.
I always felt, as did he, that whatever our problems with each other, this did not involve the children. However hard it has ben for both of us in the past (and it has been hard), we both knew that we were the adults in the relationship and that our children all meant the world to us and that happiness/settlement came first.