How long do you allow for posts to be edited?

I have mine set to 15 minutes for "untrusted members" (that could be spam bots that edit in a link later) and they're automatically promoted to 12 hours after some time.

I haven't set up DMs yet because I haven't seen a problem there yet.

My forum doesn't have a time restriction on users to edit their posts.

So for my site, if you're new user with less than x amount of posts then you'll have only 30mins to edit your content. But once you get passed a certain post threshold then it's unlimited.

The reason we have it like this is to help preserve the content so it can help someone later on if they need it. However, because we don't offer a "delete" button, new users will sometimes edit the post to contain "Delete" or "Solved" which doesn't help anyone. We would rather have you reply to your thread saying you solved it this way etc.