Yes, many ways to express strength imrpovement; agree with Bazza.
For powerlifters and olympic lifters, low reps obvious (at end of program). Skill and absolute strenght crucial, although i have always hated low reps personally.
For a bodybuilder, max reps on 80% and 70% can tell the story.
If you mix it up, the tests will be related. I can get about 20 reps on 70%, and 10 reps on 80%, supposedly i have slow witch fibres. Last year dide 137.5kg sincle bench, and 16 reps on 100kg (which is about right for me). (70% of 137.5kg is 95kg).
However, also read Ted Arcidi did 20 reps on 495 pounds wit 700 pounds single bench, although would not have a clue if true.