Think about it, what an assinine way to check oil level... wait a "few minutes"???? Define that... like Fred said, if it's cold and you don't fully warm it up, the oil will drain back slower and give you a different level. And knocking ourselves out trying to get it "halfway between the upper and lower marks" ?? And the anal debate will go on forever.... How much oil? If you use the long filters, a tad more. Here's what I've observed and what I do now.....
Fill with 4 litres on centerstand until oil reaches the upper full mark, warm up engine to 3 bars, shut off, wait 5 minutes, check level. I usually have to add another .3 to .5 litres to bring it up somewhere between the middle and upper full mark. I'd rather have enough than not enough, and that cupful extra everybody gets anal about doesn't mean squat. That isn't enough to hurt anything, nor worry about the oil being foamed up by the crankshaft.... forgedaboutitferkrissakes!
Now I just add 4.3 litres right from the start, start up to check for leaks and assure myself of the level, and forget it. When cold the level rises to fill the sight glass, only makes sense.
What happened to the good old dipsticks..... we've all been trained to do it that way our whole lives. Too many variables in this sight glass stuff, no wonder we'll debate forever.