My understanding is Lock Time has evolved to include the entire action. Originally it was the time from pulling the trigger to the ignition of the charge.
How does that relate to accuracy? Compare shooting a single-action revolver (about 1/10th of a second lock time) to a striker-fired SR9 (with a lock time of about 7/1000ths of a second). For the S/A revolver that is a window of time over 100 times longer than the SR9 in which heeling, pushing/pulling the trigger, flinching, etc., can affect the Point Of Aim (POA) prior to the ignition of the cartridge.
At 5 yards it is hardly noticeable. Push the targets out to 50 yards and the differences will be exponential.
The same is so with rifles. Most people would agree that an inline muzzle loader is more accurate than a flintlock. all other factors being the same except for lock time (meaning use the preformed propellant pellets, conical saboted bullets, fancy fiber optic sights on both rifles).
On 1911s lock time is reduced dramatically with the installation of titanium firing pin, hammer, hammer strut, and mainspring cap. Less weight = shorter lock time. It made a noticeable difference on my Springfield 1911A-1.