Can anybody suggest some "canonical" routine strategy for deleting post attachments?

I already have developed such a strategy for cancelling thread subscriptins: To cancel all (ok, no rule without exception...) subscriptions to threads that haven't been posted to the entire last month at the start of each new month has proven to be reasonable and normally cuts down the total number of subscriptions by about 50%. And if there should be a post to one of my older threads in a forum I monitor regularly, I'll most likely see it anyway.

I think, however, that this strategy is not that appropriate for attachments, as deleting them may significantly reduce the usefulness of the posts for occasional readers. The download count in the list of attachments in my User CP doesn't seem to be a real help here, as it's a total. A count over a certain period of time might be more helpful in this respect.

Storage capacity is no concern so far: The 14 attachments I have online at the time amount to a total of 139.1 kB (of which almost 50% are occupied by one single attachment). But I think it might be clever to start doing some housekeeping before it piles up to real work...

I have seen some pretty old posts that still have attachments, but I think many (if not all) of them were made by moderators, who might have more storage space at their disposal.

Any thoughts?

TIA