Well, DH and I separated a year and a half ago and we have been doing loose 50/50 (sort of). I really spent much more time with them (for ex. all the daytime while he works), but the OVERNIGHTS were split evenly.
I'm very egalitarian, and believe that we both have equal rights to the children. I know that 50/50 has not been the courts first choice for some time now, but it seems that anything else would be very difficult and painful.
Our kids know they have two homes, not "home" and "dad's house", and they know both of us are involved in their daily lives, rather than having a serious M-F parent and a fun weekend parent.
By the way, we have a 6 year old dd and a 3 year old ds. I did notice that for the first few months it helped to discuss the weeks plans with them so they could adjust to my new apartment and the routine of going back and forth from daddy's house. We have always split the week into M/W and T/TH and then do EOWeekend also. So the kids see each of us throughout the week, but we also have long weekends to go out of town with them if we want, etc.
Last month, I took the kids to South America for 30 days, which was grueling. This whole month, their dad has been "in charge" of them for overnights. I've still seen them nearly everyday (70%?) because he brings them here before he goes to work and I take my dd to school and then pick her up, and hang out with them unti lhe gets off work, plus keeping them here on nights when it's convenient for us all. But, in truth, its great to let him do HIS share of the parenting. To let him deal with poopy pants and lost Webkinz, because I do my share as well, and honestly, between work and college, I need the downtime!
But, anyways, the separation was really no big deal, nothing traumatic. I def think it helps when they have each other, too. My kids spend more time together than they do with either their dad or I, and there is something precious about that.
Also, I don't know if this comes across as sad or just realistic, but I think kids:
1) that age don't know any better yet, have no expectations of marriage lasting FOREVER the way we all do.
2) probably know alot of other kids who parents have split up, or were not together in the first place.
3) are very resilient.