Can't site stay cached

I have a site that i want to be completely cached all the time, i’ve made the preload so it runs once a day to update if any changes were made.

For some reason it seems like something is clearing out the cache prior to the next sheduled run of preload, i don’t understand what it is.

As far as i can tell the garbage collection should be disabled when set to 0 and i’ve set it to zero, so why is my entire blog cached for about 4-5 hours then all of the sudden it’s back to only caching the pages that have been visited recently.

Any ideas?

https://wordpress.org/plugins/wp-super-cache/