We separated 15 years ago when the children were 5 & 2.
From the beginning they stayed with their dad 1 mid-week night and 1 weekend night & the following day every week.
The weekend night alternated, so one week Fri night & Saturday and the next week Sat night & Sunday.
The midweek night was initially Tuesday and he'd drop at school/childcare the next day. It then changed to Monday for logistical reasons.
School holidays the first year were more with me, but after than were 50/50.
Christmas and New Year were alternated, although I don't celebrate New Year and their dad does a family thing so over the years they've been with him more on NYE than with me.
The above worked REALLY well in terms of lots of contact with each of us - they saw their dad on 4 out of 7 days a week, albeit it only the evening or the morning.
It wasn't so good in enabling us to do things at the weekend, and for a few years we had a rotating 1 full weekend each a month and 2 split weekends. For various reasons that stopped and we went back to split weekend, but agreeing to the while weekend or swapping the days if something was happening - and neither of us were unreasonable about agreeing this.
The children are now 20 (at uni) and 17 (Yr 12). The 17yo broadly sticks to the above, agreeing different arrangements with us both as suits his/our needs. He makes his own way before and after college in the week, but is transported at the weekends due to rubbish public transport mainly.
They both had a room at their dads, he ensured homework was done, he took them to a club on his evening and to their sports at the weekends, he took them to friends parties at the weekend etc, he sorted their haircuts, he ensured they had clothes to wear at his his, they had toys, and bikes etc there. Things like coats, footwear & soorts equipment weren't duplicated, so we'd each make sure they had those where needed.
It hasn't been easy, on anyone probably - and I will always regret that their childhood wasn't 2 together & happy parents, but I think in the circumstances we've done a reasonable job of ensuring contact with both parents while also providing stable bases.