We do 50:50 with DSD. This is something that both DH and his ex were committed to providing her, back when they split up (she was age 3), and it is something DSD wishes to maintain, now that she's older (age 9). Her rota is currently a full week at a time: Monday evening to the following Monday morning.
We live about 5 miles down the road from DSD's mum, just one school district over. When we were house hunting a few years ago, DH and I limited our search to areas nearby enough to do the school run. All parents (me, DH, exW, and exW's partner) work full time M-F hours, so DSD goes to a child minder before and after school every day. DSD is registered to the primary school nearest her mother's house, so she has to get up earlier in the morning when she stays with us. The traffic gets pretty bad during commuter hours, because there are a ton of industrial estates in the area too, so a 10-minute journey any other time of day takes DH and DSD about 30-40 minutes.
She is mildly annoyed by the morning and evening commutes when she lives at Dad's, but she also has a very close relationship with DH. And he and I have a baby together, so these car rides are a chance for just the two of them to talk and catch up. Baby comes with me in the mornings to go to a nursery in a different part of town.
DSD has said a couple of times that when she's older, she might like to do two weeks at a time in each house. But, we'll see how she feels in a few years, when her friends are more a part of her life. DH and I would like to get a larger house in DSD's school district, so we can get rid of the school run commute and make our lives a little easier, but at the moment, that's not really feasible. We might try to teach her to take the bus once she's in secondary, but she's got to work a little harder at being less daft.
Six months ago, she still couldn't remember our house phone number. And she still doesn't have a Scoob what her mother's number is.
DH and his ex had a very amicable split, all things considering. She called time on the marriage and moved out, and once he recovered from the shock, he was happy to draw a line under it. I envy his ability to do that; if it happened to me, I probably would have been bitter for the rest of my life. But, the two of them speak to each other respectfully. Emotions ran high during the first year or two of their split, but each year that goes by, they're a little more relaxed.
It wouldn't have worked if exW was the type to cut off contact. She wouldn't have suggested 50:50 in the first place when she split with DH, and would have gone for a more common EOW arrangement. It also wouldn't have worked if we didn't live nearby. For the most part, DSD is DH's and his exW's responsibility, but the step-parents pitch in when needed to support our partners. During maternity leave, I picked up DSD from her childminder at an earlier hour, and sometimes took her to school as well, to make life a little easier on the family.