Cylinder #7 down on compression

So a compression test is not a good test for overall condition of each cylinder? My compression test produced 7 holes of 140 or more and one of 105. With all the plugs out and the block stone cold. I don't consider that worn to the point that I need a complete rebuild. #5 was one at 140 PSI. Maybe I'm wrong but I'm an IT guy and not a mechanic.