Also work in defense, this is becoming pretty common. Although typically everyone takes the same friday off - that saves operating costs (no janitors or cafeteria on the off day). There's also the benefit that people tend to plan their vacations around the off-fridays, and work the full day on on-fridays. So you don't get stuck at the office trying to solve a problem with nobody to answer your questions at 3 on a summer friday.

I believe the team in question needs to support something in person so they do a split.

I was providing a counterpoint to show that it's preferable having the whole office take off together when that's possible for your business. I don't disagree that staggering the off days could be necessary, but it isn't ideal.