Thanks for the answers! I did a backup, and the actual result was it will recalculate the Count so if a pilot would have a wrong count it would be corrected.
Sometimes, I need to just fiddle around to learn about the admin section 😅
As @Parkho suggests, back up your database first. Then, if it doesn't do what you think, you can always restore.
I always thought it recalculated the PIREP count - but I've never had a reason to use it on my live site. But I have been wrong before (just ask my wife 🤣).