I try to avoid this if I can. I have a nice snap-on torque wrench I use for automotive things, or at least I did when I used to have time to wrench on cars. I inherited the snap-on though, if I had purchased it on my own I would've gone down-market a bit anyway.
I like the confidence of knowing things are torqued to spec.
Just a note or suggestion but I'd venture a guess that if you're using a standard straight shafted screwdriver your torque values are coming up shy of spec. I like to be precise.