Oh, my—look what I just found unpacking a box after my move. It's a bit anomalous, in that I never used a IBM 1401, though I did have a bit of experience (though not in assembler) with the 1410. Note the columns labeled "assembled instruction"—on some systems, including the IBM 1130 that I had a lot of experience with, the assembler could punch the binary into a card—useful on diskless or low-disk systems. Yes, you'd have to use fresh source cards when you changed the program, but that wasn't hard; the programmable—and by "programmable" I mean "changing wires on a plugboard"—card duplicators of the time could easily reproduce just the source lines and omit the binary from the last run.