If you were really lucky (and it wasn't too close to end of semester), you could get three runs of your job in the four or five hours of lab time available.
Lucky beggar. My first job was programming in COBOL, at a location where we had no card punches. We got two runs a day. We *wrote* editing commands for our card decks on coding forms, sent the forms and decks out to the keypunch center, got the updated decks back. If the keypunch center made a mistake we got to make a few manual changes at the console after reading the deck, but we had to remember to make those changes in the next editing run as well.
We got pretty good at using old cards over.
