A single trigger is not like the LED in your dogs training collar, in that it either works or it doesn’t. They are made and fitted by humans, to a substrate (wood) that is subject to expansion, contraction and outright breakage over time. They come in mechanical, inertia, non selective and selective versions, and there is no guarantee the manufacturer stuck with the same version over the time the gun was in production.
The evolution of the Browning Superposed trigger is another solid example of that. Double triggers, Single non-selective,
Twin-Single triggers, single selective (inertia) with the selector next to the trigger, single selective (inertia) with the selector as part of the safety, single selective (mechanical) with the selector next to the trigger, and the "Olympic" which is a version of the latter.
The inertia triggers were known to not work great in the smallbore guns with light loads - my daughter's 20 gauge being an example of this.
