[Plugin: WP Super Cache] garbage collection

hello.
i have tried to check whether garbage collection works as said in super cache’s admin panel. i have set expiry time to 30 seconds, so garbage collection should run after 40 seconds, but cache files have not cleared after 40 seconds. then i have tried to delete them clicking “delete expired” and then recteate by opening the page from browser, but after 40 seconds they again has not been deleted. in “cache contents” section of admin panel is written:

Garbage Collection
Last GC was 03:56 minutes ago
Next GC in 56:34 minutes

Expired files are files older than 30 seconds. They are still used by the plugin and are deleted periodically.

( at that time, when i deleted and recreated cache of page, time was 10:27 , even if it means 10 hour 56 minutes, it is too long .)
So this is intended! So explanation of garbage collection is wrong?

This has been reported as bug in previous versions, the topic is closed: https://www.ads-software.com/support/topic/plugin-wp-super-cache-garbage-collection?replies=10 .