i tried this experiment myself a while ago and heres what i found out. Im guessing the results vary on how you get yourself off, whether your hand is tight, how long you make it last, etc. Personnaly i try to take as long as possible when masturbating and am usually pretty tight. But anyway this is what i found:
Stamina: i couldnt go for long if i hadnt been wanking, however if id been having 2/3 faps a day for the past week then i took a good amount of time to cum. usually about an hour.
Erection: without masturbation i got aroused at almost anything, but didnt neccaserily stay hard for longer or watever. With masturbation however it took usually touching/pinching/squeezing etc to get me hard.
Amount: I'll tell you wat tho, if i didnt wank it felt like all the orgasms i should have had that week were compiled into one. It felt mindblowing! however it left an exit wound in my girlfreind
