These new forums are taking time to get used to. Forgive that I'm asking a question I almost certainly bet has been asked before; I can't find anything.
I read somewhere back in the days of undergrad that this has to do with optimization by reserving groups. (Kind of like how some file systems spread stuff across a disk maybe?).
1. Can I adjust/disable this functionality?
2. Does it ever back-fill in the gaps?
3. If so, when does it do this?