P: Improve the Preview discard options

The only choices today for managing previews are to set a fixed size limit (very useful if that drive doesn’t have unlimited free space) OR remove 1:1 previews after ‘n’ days. And if you set a fixed size, you get nagged constantly about increasing the cache size. 

First, why on earth can’t we have both choices active?

Second, more options for how to manage the retention and discard of previews from the cache would not be especially complicated to implement but would speed editing. 

The principles of buffer management are common to many kinds of IT systems so there are many approaches - including algorithmic guesses at what might be viewed next - that would improve the chances that a suitably sized preview is found in the cache when needed.