I used to carry a Glock 36. When I started carrying with a round in the pipe, I was not fully confident in my ability to practice absolute trigger discipline. Loved everything about that gun except that it had no safety.
The safety was one of the reasons I bought the Shield. I carry safety-on. You have to develop the habit of swiping the safety with your thumb as you bring the gun to bear.
If you are fully confident in your trigger discipline you can forgo using the safety. I may reach that point sometime, but for now, I'll use the safety.