[Plugin: WP Super Cache] Should not cache update hourly?

Hi,
I was under impression that with setting “3600 sec” cache timeout and enabled garbage collection my cached pages would be updated every hour. However, I see in the html source of some pages that were cached a month ago. Am I doing something wrong or misunderstanding the process?
I use PHP caching, most other recommended settings, and GoDaddy hosting.
lzr

https://www.ads-software.com/extend/plugins/wp-super-cache/