How many rounds could someone fire through that cannon before it starts to deform from overheating? In other words, is there a practical limit on the number of rounds fired before it has to cool?
Rate of fire makes a difference in how quickly one can do a follow up shot. You actually wouldn’t run that many rounds in a minute but you can place a few rounds on target more quickly.
Rounds per minute is cyclic rate. Its never intended to convey sustained fire.
For example an M61 Vulcan cannon has a cyclic rate of 6000 round per minute, but the magazine is limited to 400-500 rounds. So it can fire a few 100 round bursts.