I can do trivia lol....good read and thanks
Go see Professor Google using piston drop vs crank rotation calculator as your question.
When you find a calculator plug in some numbers and you will see when you get close to TDC ( or BDC ) you get a massive amount of rotation for a very tiny amount of piston drop.
That is why the piston stop method mentioned earlier is the only method worth using for Joe Public.
I have used the valve fully open while adjusting the other for all my life as I was brought up with BSA motorcycles that use substantial opening & closing ramps.
Also take in the comment that you are working on a lawnmower in a very soft ( thus forgiving ) state of tune and not a NASCAR top fueler.
I get mowers in all the time with either no valve clearence at all ( no I never let it run out of all what makes ou ask that ) or clearances that are 2 to 3 times bigger than std.
Most of them are running when they come in they are just had to start ( takes 1/2 can of starter fluid ) or arn't quite running right ( doing 4000 rpm or unable to exeed 2000 ).
Sprit series are really low tech, low tune & thus very tollerant to low / no maintenance