I'm not quite sure how much compressor run time should be, but If its the same as a fridge, ambient temp does play a huge roll. I don't know how accurate this is, I was told this by another tech, not a book, or a school but.
A good rule of thumb is:
The ambient temp around the machine is 90 degrees
That machine will run 90% of the time.
The ambient temp around the machine is 82 degrees
It will run 82% of the time.
Now this is a good rule of thumb for a Fridge like I said. I don't think it will apply to a Air conditioner.
I have way less experience in Air Conditioning.
I bet one of our other techs will be able to help you out alittle better then me.
Now if it was a Maytag washer. I'd be all over that for ya!