Like most everything in life, it's a balance. Carrying a tourniquet is a great idea. It's much more likely to make a physical difference in the real world then a spare magazine. I seldom carry one in the summer, I just keep them in my vehicles. I used to carry a RAT but apparently they suck and I've not gotten a tourniquet holder I like for regular attire. I am objectively less prepared for bad things happening due to that. But I accept the risk of having it in the car instead of on me.
Side note: I need a covert tourniquet holder. Ideas welcome.