The shorter the lock time, the less time there is for the gun to move off aim during the firing process.
Also, if you have a heavy and slow hammer, the reaction to the hammer fall can cause considerable movement during the hammer fall along with the sudden release of pressure on the trigger finger. This can result in a significant change of point of impact depending on whether the gun is lightly or loosely gripped by the shooter.
You can see this if carefully dry fire a single action revolver that has a scope on it. When that hammer drops, you will see the image jump, even on sandbags.
I found this out when I was shooting a flintlock pistol at a target. Even though I wasn't jerking the trigger or flinching, a lot of my shots went low, way low, nearly missing the paper. What was happening was the sudden release of the trigger pressure was allowing the barrel to drop during the ignition time. I firmed up the grip of my middle, ring and little fingers so that my index finger's only job was to move the trigger and that problem went away.
On a modern target pistol with a fast lock time and almost no trigger backlash, I probably would never have discovered how the grip was affecting accuracy and point of aim.