Jeep
At first I didn't care for the manual safety but after practicing pocket drawing sweeping safety and squeezing the trigger I wouldn't have it any other way. (Always practice drawing with an empty weapon!)
I pocket hot and with an excellent holster (Desantis) I cannot make contact with the trigger while properly holstered and the manual safety adds that extra safety and when I pocket hot I want that added level of security especially when I sit at a desk all day and muzzle point.
Practice with the safety on, then it becomes second nature, you don't even think about it. You just naturaly sweep it off. I always carry with mine on, always have. I even find myself sweeping it when picking it off the bench at the range. I would rather be safe than haveing a bad moment reholstering. Picture yourself explaining why you have a hole in you butt or thigh in the Emergency room. Another thing to consider is your weapon is on your desk, and someone picks it up. Safety on, even the most inexperienced person can not pull trigger. And if they do, at least you tried to stop the accidental discharge. My wife handed me my 1911 one day with one in the chamber and cocked, we had a discharge, shot out the tire on my dolly. Good thing I practice always treat every firearm as if it is loaded. Gun has a hair trigger, and that is why I don't carry it.
I considered a Sig 938 for pocket conceal which is a little lighter and smaller than the Shield and shoots just as well but I cannot bring myself to pocket packing a weapon with a hammer locked in the firing position. I know many will argue it is safe but I like the design for safety of the striker fire Shield with multiple safety features including the manual safety.
Russ