I appreciate Gabe Suarez and his company Suarez International. Like every organization they have the weapons they advocate and are out to make a buck. Hey capitalism is cool so that is all good. Awhile back (not as I am writing this but as you are reading it) they did a lot of talking about safeties and the finger on the trigger.
Gabe Suarez made a great point that the M1911 and the AR-15 have done a lot to influence modern training when it comes to weapons safeties. I think that these two weapons were for so long the weapons our military carried is significant. No matter how much folks don't want to admit it most weapons, training and techniques stuff trickles from the military to law enforcement to civilians.
If a weapon has a super fast (AR, M1911, M1A, most DA auto's, Mossberg 500, etc) and easily accessible safety then use it. If in the case of say the AK or the Remington 870 the safety is not so accessible then don't worry about it. With the AK I would just take the safety off when I thought I might likely fire and with the 870 I would keep the chamber empty unless I might likely fire the gun. While this might be a slight generalization modern firearms aren't going to go off while you carry them unless you pull the damn trigger. Most have mechanisms so they won't fire even if they take a sharp impact unless the trigger is pulled.
Physically accessible safeties IMO have a lot more to do with people's psychological comfort than actual mechanical functionality. A good friend and experienced shooter who is my buddy is half scared of his Glock 19. He has shot more guns than most folks I know but is just used to semi auto's with a physically accessible safety.
Personally in terms of handguns I grew up on double action revolvers. They don't have a 'safety' but that big heavy trigger pull makes sure you don't fire it on accident. In any case it is psychological. The trigger makes the gun fire. My first handgun was a Glock .40. Again if you don't want to shoot the thing you don't squeeze the trigger with your nose picker. Really not complicated. I guess it is something you are comfortable with or not.
Finger on the trigger is to me a more complicated issue. It is also a great example to show that life is not black or white but full of grey. By far off the trigger is the way you should train and get muscle memory. However I think there are some situations where one might put their finger on the trigger and not immediately shoot. For example I know a guy who is a cop. He pulled a guy over for a half dozen infractions (the vehicle had issues and he had a suspended license and tickets) and as soon as he went towards the truck the guy got out and grabbed a machete from the bed. Needless to say the cop pulled out his gun. The dude was about 18 feet away and just standing there with the machete. My buddy had his finger on the trigger and as he said it he had about 7 pounds of pressure drawn back on that trigger. He started talking to the guy (he was in a bad spot needing to get to work but having a suspended license, a truck that has issues, tickets, etc) and eventually got him calmed down.
Personally at the risk of generalizing I see it being situations where there is an identified threat and you may have to shoot. I would not put my finger on the trigger unless there was a definite target. The reason I would not squeeze the trigger is that the threat had not forced me to shoot. YMMV.