Yeah, I've debated that point with myself repeatedly, so my thinking went something like (this only partial logic, but you get the idea)...
On my laptop I have only a single drive so there is simply no choice.
However, that drive is BitLocker protected and is backed up every single day. The backups have 2 additional copies replicated to other locations including one offsite location.
In addition, all that data is in a single place so if need be, all I have to do is backup a single folder with subfolders and that is everything. There is no accidentally forgetting that some stuff was off in some weird corner somewhere.
In order to have some consistency, I do it the same way on my desktop computer.
Note that this may not be what you are really thinking - It's just word docs, spreadsheets, misc stuff, etc. In grand total, this stuff that I need ready access to is barely over 1 GB in size.
All my big stuff - ISO images, software assets, and a lot of other stuff totaling maybe 400+ GB is on a separate drive for the desktop and an external drive for the laptop. Again, multiple copies are backed up every single day. Plex is whole different story. The Plex server runs as a VM to it's a super easy to backup because it's simply one unit - the VM. The data for Plex is separate and accessed via UNC share names. That way, if the VM is ever moved, it doesn't matter. Access is still to the same UNC shares. Last time I specifically checked the size I think that VM was only like 50 GB. The Plex data, however, is about 6 TB so far, and yes, it is backed up every single day.
My job for over twelve years with a major storage company was to help top enterprise customers to protect and recover data on our mission critical systems so I've seen my fair share of planning both good and bad. Makes me highly paranoid about how I handle my own personal data :)
