I used a 300 watt halogen floodlight which nearly blinded me. I had used LED lights but the light I felt was not as good
I do agree that with considerable effort a zoom can be treated to a "compromise setting" by e.g. checking my 24-70mm at 24, 40, 55 and 70mm and then calculating an average setting. However, I am not sure where the fine tune setting should be decided on. I tested at 24, 45 and 70mm and got all + fine tune requirements +15 (24mm), +5 (45mm) and +10 (70mm). So I knew the lens was front focusing. So I ran a test at 45mm from 0 - +10, the result was +5. In the end I decided on an average of +7 as a half way house.
I re-ran the test throughout the same focal values, but instead at the closest FocusTune distance, 50% of maximum (because the distance tool told me to use the long ruler, which I didn't have). The results were not even comparable to the first results with +20, +15, +18!!!! At that point I must admit I gave up for now and returned the AF-fine tune to zero