If my goal is a 36g shot, is pulling the cup away at 36g the same as getting the machine timed just right so the last drops get it to 36g? [Breville barista express]

Lately ive been trying to dial in my shot by ratio (2:1), 18g in, 36g shot out. Trying to hit that 36g means getting the machine to stop anywhere from 28g to 33g... then letting the 'run-out' get it to 36g.

This has been hard to nail just right, sometimes I see it getting ready to blow by 36g and i just grab the thing... which has me wondering, how much does it matter? If I just pull the cup vs. getting the machine timed just right?