I've had use for it maybe 2 times. Since I've only been hunting with a muzzy for 8 years, I consider that often enough that I should pay attention to the issue.
The one time I made the rookie mistake of shooting at a running deer and hit it too far back. The deer ran about 50 yards and just stopped there, looking at me while I was frantically reloading. The 2nd shot transversed the 4th cervical vertebrae, taking care of that issue.
The other time I took an offhand 150 yard shot, and again hit the deer a little far back. Instead of bolting, it went 20 yards and bedded down. I still had a clear broadside shot of it bedded there, so I took the 2nd shot and my aim was better that time.
So both times a fast follow-up was necessary due to mistakes on my part. I can see how if you are very picky with your shot selection, a quick follow up may rarely be necessary.
I wasn't timing myself, but both times I'd wager that I was reloaded in less than 30 seconds.