I was just wondering if there was a formula to find how many seconds it would take to run through a gear. I would assume it would be directly proportional to the RPMs of the engine and the torque (after the final drive ratio is considered)...

Anyone know?

Its all a function of engine rpms, torque converter stall speed, shift kit, clutch material, etc.

So basically... Too many factors to ever possibly begin to consider and be accurate... Better to take experimental values (time it yourself)...

Yep.
Time it yourself.

I just rebuilt my 4L60E tranny in the '00 Blazer and my shift times got longer. I used all high performanc parts, kevlar clutch materials, pinless accumulaotrs, etc. My tranny will hold gears much longer then the stock unit, and I didn't change any of the computer programming.