Once you have gone through the process of moving the film from the 120 spool to the 620 spool, you still need another 620 spool for the film to wind back into as you take the photos, right? And then once the film is spent and rolled onto the second spool in the camera, do typically send that spool in for developing or do you then spool it back (for a 4th time!) onto the original 120 spool so that you are sending that back in and keeping your 620 spools? Otherwise it seems you’d be running out of 620 spools quickly. Sorry if I’m misunderstanding this all, but I just acquired my first 620 over the holidays too - a Kodak Jiffy Six-20 Series II from my mother’s boyfriend. He has owned it since it was new!