Hi Dan,
I have run across a very few shooters who had such good trigger control, they stopped pulling once the sear released the hammer. So, yes, that could be the case in a small percentage of shooters. What you are saying, in my experience, was more common with Pistol Shooters and we had a very few shooters like that on The Marine Corps Pistol Team over the years. A very few of them had such good trigger control they could actually stop the trigger pull during the break and delay until they felt they were back in the center of the bullseye. WOW where they tough to build a trigger for! Grin. So I have sympathy with what you went through on SA Colts. Of course as you know, there is no fly on the hammer of a SA Colt to keep the trigger/sear from hitting or going into the half cock notch.
I was never a .22 Rimfire Rifle Collegiate Shooter, nor what we called an International Shooter on The Big Teams in the Corps. However, the International Shooters told me that they (like Collegiate .22 shooters) were trained to release the trigger right after it broke, so as not to throw off the rifle or pistol as might be caused by continuing to pull the trigger. It was especially important with the Hammerli International Bolt Action Pistols as they had a trigger pull so light, the force of gravity set them off when they were raised to or just above 45 degrees.
The other thing about musket locks is even the original ones were a little looser in tolerances than good civilian locks. The repro locks often are even looser than that. So sometimes when one thinks there is clearance between the sear tip and the half cock, the half cock hits the sear tip as it goes by. This is extremely frustrating on Smith Carbine trigger jobs as it is so difficult to judge how close the trigger/sear and tumbler are when the action is not assembled. On muskets, one can put the tumbler in a bare lock plate with the bridle and screw plus the sear and screw and hold the sear in place just as it clears the tumbler. Then by slowly turning the tumbler, you can see if the half cock notch hits the sear face. I found it was normal to ensure the sear cleared the notch by a little more than just not hitting as the tumbler went past, though, because of the looseness of the tolerances. So if one did not use a normal trigger pull with good follow through that will pull the sear face further back out of the way, it lessened the chances of the sear hitting the half cock notch. Of course, if the shooter released the trigger pull just after it broke, it would almost certainly allow the sear face to bash into the half cock notch.
Another thing that I found common on the cheaper repro locks was the wood clearance for the sear bar was often not enough and the wood kept the sear from being pulled away from the tumbler enough. So I always checked for that and cleared that first.
Working all those NSSA military locks really helped me to work on Flintlock Military Locks, as the internals worked the same way and were also a little looser than civilian locks. However one Brown Bess Musket owned by a member of my reenactment unit about drove me nuts. After working on the lock and ensuring the sear bar did not hit the wood, it STILL occasionally allowed the sear to hit the half cock notch. I have to sheepishly admit it took me about 45 minutes to figure out the trigger was hitting the trigger guard at times and not allowing the trigger to go far enough to the rear to push the sear face out of the way of the half cock notch. WOW, did I feel silly for not realizing it sooner. After I cleared the bottom of the trigger, the problem was completely solved.
Gus