You basically answered your own question

If your engine makes 5 minutes and a lap, (you might cross at 4:59, and pitting on fumes sucks) then you are basically good. Time is always what you look at when trying to make a decision like this. No engine likes to be at the rpm limit like how we constantly bang the 21's in 8th scale but it's how it is and you just have to replace the bearings. Off corner zip can be had from the clutch.

On the flip side to that, I did see Mike Swauger pit at I believe 4 minutes flat at the nationals and switch tires halfway through the hour and was ahead by a lap at the switch, and then ahead by a lap at the end. Everyone else was pitting at 5 and nobody else switched tires except his pit man is spectacular so he can do that. Fuel and 4 tires in 16 seconds. Mike did pit at 4:?? in the qualifiers and it wasn't good for TQ although his pace before the pit was always low.