Cache has an upper limit and will not go past that unless you fiddle around in a browsers config. It can become out of sync but if so the browser will flush tha

Cache has an upper limit and will not go past that unless you fiddle around in a browsers config. It can become out of sync but if so the browser will flush that data and reload from the web. All of this is automated so the user doesn't need to do anything. There are some rare occasions where the browser can't seem to sync the cache with the online data and manually clearing it is required. Normally this will presented as a broken website. The cache exists to make loading faster due to the difference in access time between the web server and the local memory store (disk). So no do not clear your cache manually every month. The advice makes no sense.