You are correct that it is pointless to delete things twice. However you are wasting your time and defeating the purpose of the system by emptying your recycle bin.
Unless you are running some ancient relic of a home desktop, storage space should hardly be an issue. When deleting extremely large files they bypass the recycle bin and are directly deleted...so there is no need to pedantically empty it. As you noted, it is a waste of user time to do so.
However I can't tell you how many times I have found occasion to desire something that was previously deleted...perhaps months ago. Sometimes we make stupid decisions. Sometimes when going through and cleaning up files we accidentally delete the newer version and leave the older version. Sometimes when working ona project we make changes that later on don't end up working out so well and we decide we want to roll back to a later date. There are countless unpredictable reasons why we may want to retrieve a previously deleted file.
The correct way to use the recycle bin is to delete things and then forget about them. If you ever need that space, which you won't, you can manually empty it. Until that time, it is a waste of your time to empty it, and will probably come back to bite you someday when you realize it was a providing a function that's actually useful.
I think anyone who swears theyve never needed to recover a deleted file is either full of it or has a bad memory.