Hi
At least up to VP version 10.43....
The cache does not clear automatically. You have to do this yourself. If you never clear it. it will continue to grow with every project you create. (At least up to the value noted in Options/Disk. ) and using large files will fill it faster.
If you have a project open and are working on it, Options/Disk/Clear Unused Cache Files will clear out all the files apart from those used by the current project.
If you have Saved Project or Saved project As you will have created a .vpj file. It is good practice to save your project regularly.
If you don't load a project and you clear the cache, or manually clear the cache totally, then if you open the .vpj file,( and provided you have the clips/images/Audio) etc. still on your PC,) VP will reconstruct your project and restore the cache using only those clips. If you have removed/renamed/deleted any clips you will be asked to find (resolve) them.
Unless you intend to return to a project it is advisable to clear the cache after every completed project. If you never save your work and clear the cache you may not be able to restore your work.
Nat