Well, normal sunny day is like EV 9, cloudy ranges from Ev 6-8.
I set-up FoCal chart on my wall, and camera was on tripod and ran the program 4 times, same distance, same everything except different time of the day. When it was sunny I needed MA of +3, cloudy MA of +9 and florescent light MA of +15.
I did calibrate my lens on cloudy day, with EV 7.5-8, and on sunny day you can't really tell if it miss focuses, maybe slightly if you pixel peep. However when I took pictures during tungsten/fluorescent light (basically indoors, and it had plenty of light), it back focused heavily, like every single picture was out of focus. Next day I go outside and take a bunch of pictures, and they are all spot on.
So I re-calibrated my lens in fluorescent light, and now indoors it focuses spot on, and outside it front focuses. This is very annoying as I love the lens and but it constantly misses focus.
My 30mm f/1.4 wasn't as bad on my 40D, but 35mm on 6D is like unusable.