In the wp-super-cache page, there is the following sentence, which I do not understand::
Checking for and deleting expired files is expensive, but it’s expensive leaving them there too. On a very busy site you should set the expiry time to 300 seconds.
Let's say that I am using a low expiry time, doesn't that mean that the cache needs to rebuild over and over every 300 seconds?
I mean, most of my content (except for the home page), does not change. So why should I matter if most of the posts will simply stay the same for days?