> The only time when GM will definitely analyze more lines than an amateur is in a highly tactical position

Those critical moments are a big part of the difference between a GM and a good club player though. If a GM was somehow handicapped to not calculate such tactics, I think lesser players would be able to draw games against GMs much more often.

I agree that GMs can avoid calculation in many positions (e.g. openings as you said), but the value of broader and deeper calculation is still huge in chess.