"several Linux distros installed and which all share a common /home because I apparently like to make life difficult for myself"
It's actually a recommended way of doing things by some distros, to the point they'll do that automatically if you don't tell it otherwise. Separate /home and /boot. The reason for /home is so you can share it between distros. The reason for /boot is that in the past you had to have that near the beginning of the drive, something that hasn't been true for a long time.
"that's as close to a logical reason I have for having multiple distros installed on one machine"
I have one machine with over two dozen different operating systems on it, mostly Linux. I have a micro SD card that I call "Magic Pixie Dust", with all those distros on it, so I have a variety of choice if I have to boot into something to fix some one else's computer, demonstrate something, or just offer them a choice of distro to install. I keep the master for that on the second hard drive of my test box, with the boxes usual WIndows / Linux on the first drive.
I don't share my /home, coz different distros, and different versions of distros, have different versions of applications, some of which change the way their config files work. In particular tmux which seems to change the names of options I use with each release.
I usually prefer the "one big partition" scheme. Otherwise you invariably run out of space on one, while having plenty of space on the others, then you need to juggle files and symlinks, or resize partitions to get things to fit once more.