Santafecino
button man
You are doing the right thing. It's the best check on exposure and development. I do proofs of all my 35mm and 120 rolls. It should be done to a fixed formula--once you find out your correct exposure index and development time. (see the Zone VI Workshop) Then you can expose any number of proof sheets to a standard exposure to give a black film edge, put the sheets in a paper box, and develop them efficiently by time. I can do up to maybe 10 sheets at once, agitating by picking the bottom one out and putting it on top, then the next one . . . Make sure your fixer is fresh; you'll do a lot of paper. It's much the best way to judge your pictures.