In less than 10 months the disk on my new custom PC I built specifically for play Microsoft Flight Simulator is already full:
I put a 500GB m.2 NVMe drive in this machine, so while 500GB is not massive, it’s surprising that the updates, patches and scenery cache so far has already filled the entire disk. This main NVMe was a Corsair Gen 4 m.2, so was slightly more pricey than alternatives but faster than the other Gen 3 m.2 sticks at the time. I have since added a second 1GB m.2 stick, a cheaper but not as fast Sabrent Rocket.
Rather than reinstalling MS Flight Sim from scratch (which would have required another multiday download from Steam), I moved the packages folder from C: to D: – steps to do this are described here.
In summary for Steam installs, edit the UserCFG.opt file in this location:
C:\Users\YourUsername\AppData\Roaming\Microsoft Flight Simulator
… and change this line:
InstalledPackagesPath "C:\Users\YourUsername\AppData\Roaming\Microsoft Flight Simulator\Packages"
… to point to any new location. You can move the existing content of this folder to the new location, and when you restart, any new updates or add-ons will go to this new location.