We have a 2 day in office hybrid schedule, where two days are the group days where more meetings are scheduled. But it's flexible. If you want / need to change the days you come in, no one says anything. It's a large team, so there's always at least a couple people in the office on the off days.

Seems to work out for everyone. The more introverted just show up on the off days, and no one cares. Every once in a while, the manager will encourage but not insist on war room kind of gatherings for some aggressive deadline with high visibility. End of the day, work just needs to be done, and everyone is welcome to do what's most efficient for themselves.

Team seems happy enough.

It doesn't benefit them, though; they just prefer it.

There are tons of people who prefer it but don't actually get any benefit out of it.