My ex-wife screwed me in the divorce and she and the therapist that setup our 70/30 parenting plan knew it. They were not basing their plans on science, but on "what's best for the kids" mythology that has been perpetuated since my parents got a divorce 49 years ago.
The non-custodial parent is treated a bit like a second-class citizen in the legal system. If you want to go for 50/50 divorce parenting, I think you'll need an attorney. I also think it's worth it, if you want to spend as much time as possible with your children.