I worked on one team that had a one week planning period every two weeks. The planning week, for us regular devs, was “do whatever you want” and it was epic. There were basically no bugs because a few of us liked tackling bugs for fun. Other people worked on optimization problems and code hygiene.

For the people doing planning, they were always busy playing ticket shuffle, asking random devs random questions all the time. But those two weeks was cray and anything not done by the end of the sprint had to be done by the end of the planning period, and you better have a good reason.