Hi Lisa,
FWIW, it took me about 4 sessions, ranging from 1-2 hours per session, to complete the 1RM testing. You have to factor in proper rest to get the most of your testing, as you will get fatigued during this process. I broke my testing down largely by body part - legs (2 sessions), upper body (2 sessions). I did almost every exercise, but did repeat values for exercises that were fairly similar.
good luck. You will get the most out of the STS program by doing the 1RM tests, so good for you for taking the time to get those in!!
let us know how it's going!
FitGirl-ATX