Are they so different that it’s justified to have so many different distributions? So far I guess that different package manager are the reason that divides the linux community. One may be on KDE and one on GNOME but they can use each other’s packages but usually you are bound to one manager
I custom install every time, partially to preserve my user data partition, partially because I don’t like the defaults (I like mirroring my disks and leaving space to grow into later if I want)
Same here, that’s why I have 3 different drives in my PC, 512GB nvme ssd for root, 1TB SATA SSD for home, and 2 TB SATA SSD just for games/emulation and steam