Back in the days of tapered bb spindles, I would occasionally have my left crank fall off. I bought a torque wrench and found that I was only torque to 1/2 the recommended value. Problem solved.

You're not going to get any consistency if you just torque by feel. Different feels depending on handle shape and length.

That said, being ballpark close is close enough; you don't have to be exact. But if you need a torque wrench just be be close, why not use one as a matter of course.