Any firearm can and will fail under the right or wrong circumstances. Fail to fire, fail to get the next round into battery, jam, or break. Either type will be harder to reload or get back into shooting it during a gun fight. Because all fine motor skills get harder to do or will not work at all under high stress. Fine motor skills are things like making your fingers preform a task. Only lots of practice might over come that problem. Some are better than others. The 3 round, 3 yard, 3 second rule is a police number and is or was a average number, (I believe the round count is now 4.x?) not the normal gun fight that is done by non police. That number I have never seen in print.
I shoot and carry both or either revolvers and semi autos on and off duty. Yes, I have carried a revolver as the service gun and the backup a semi and a semi as service and backup a revolver. Practice, practice and do more practice with what you carry. I am not sure that I will say a revolver is better or easier than a semi to train or shoot or the reverse. I have trained new and seasoned shooters with both. If you list THE revolver by brand, model, caliber or THE semi by brand, model, caliber. Then we can discuss the good and bad points of training and shooting that gun. This post is fun just to toss around your personal thoughts but, will not answer any question or prove much, just lots of opinions. Some good, some bad.