How long will it say "recent" next to a contact number if we do not communicate again?

It was definitely not saved in my contacts under anything else. But now it doesn't say "recent" next to it. I checked and rechecked the recents list, & it wasn't in there. Seems like there was definitely a few hours delay at the least. I tried to test it with other contacts, but couldn't duplicate what I am saying happened. Thanks for your help.

I have deleted it from the "recents" list, and blocked the number. However, when I go to blocked numbers it still has the little gray box that says "recent" next to the number.

I did. it's not in there at all.

If the number was under a different name, at the time, wouldn't the name change in the "recents" list when I updated it in the contacts?

How can I find out if I have more than one?