I have it listed as 5.5 min 68F, but it has been quite some time since I made these notes. I was pretty good about changing my times in my notes if there were a problem. No changes were made.
We were using F76+ as a replenishing developer. The top off solution was mixed 1:5 , so adding it to the tank after each use must bring the actual dilution around 1:7? I was always happy with this developer. However, I was told loosely that the F60 and the F76+ are in fact the same product, only the F76+ is sold as the replenishing version. I never really got a definitive answer on the actual difference (if any) or as to why that would make sense to sell this way.
Good luck, hope that helps a little. Please post a result whether it be product or text.