Also don’t forget that you can just look in the timeline index to see a particular asset has been used in your current project. (next door to the REEL icon – bottom left corner of the X interface)
Don’t know if it’s relevant for you – but can also sometimes gain back a whole lot of space if you have multiple old projects on your drive by using the render manager to blow out presently unnecessary render files. Just open the Project library – click on your old Projects – trash their render files.
Worst case if you make a mistake is that you’ll have to re-render that project again – so only do this if you have a good strategy for storage of all the assets your project needs to re-constitute and re-render the timeline.
That said, I did this a few months back and was shocked to discover that I recovered more then 500 gigs of space off a 1.5 Tb drive!
YMMV.
“Before speaking out ask yourself whether your words are true, whether they are respectful and whether they are needed in our civil discussions.”-Justice O’Connor