That well exceeded the approved max rate of fire, but the only downside was that we would burn out that little piece that held the primer (so long ago I can't remember what they called it.)
We would stockpile those parts so that we could maintain the 5 rounds per minute rate.
The quick fire was the one where the situation was a unit being overrun, and we needed to get artillery shells into the area to let the attackers know that focused artillery was coming within minutes.
The exercise was that you are driving, and suddenly you have to stop, and the second that you can get a shell into that engagement, you fire it, and then you proceed to improve and refine your firing position.
My section used to win those kind of things, and it seems like it took, far, far less than 10 minutes, back then I would handle the over 200 pound spade myself, to free up an additional digger.