That's where it belongs?
Not to be a smartass (okay, I am) but I've adapted what I assumed was common wisdom to separate system partitions from data partitions.
So I have my system partition (C) which basically is restricted to the windows, programs and users folder.
The latter because previously it was not that easy to move it to a different location (and in my case holds no essential data) and programs because a) almost every application has to be installed anyway and b) to minimize problems with applications which sloppily assume to find programs on the system partition (kind of a leftover from earlier times where such things happened more often than today).
Everything else (MyDocuments, FF and TB profiles, a number of application not requiring install, downloads, the usual porn and other stuff) is located on other partitions. I also have my own partition for games. And while of course most games require installation steam games are immediately ready.
Advantage:
It helps me to keep the system partition relatively small. Consequently the occasional image of that partition is as small as it could be.
If my system becomes corrupt it's quite easy to simply reinstall the system (or backup from an image) without worrying about saving data. Also it helps to give a new system install a clean start by simply formatting the partition.
Also it makes no difference for backup, so no extra effort is involved.
Disadvantages: Minor adjustments after installation of the OS to adjust the links to a few folders like MyDocuments, Favourites, etc. Five minutes tops.
I'm doing that was many years now and this system has served me extremely well so far.