> In a default configuration, the data stay on a node for 30 days (I believe this is the default time period, YMMV) before it's gargbage collected. However, if the hashes are pinned the data will stay there indefinitely 

That's not quite how it works. (On a go-ipfs client)

Currently the cache is filled until the disk is filled to the brim.

There's a gc which you need to activate via a flag, which will start by default if the set size is reaching 90%.

It will then remove everything which is not part of the MFS or pinned.