If you are well-aware of how much torque you apply with your "3-finger" approach and you can apply that amount of torque consistently, then that could be a good method.
However, I think you will be surprised if you actually check yourself.
You can check yourself by turning a wrench against the square drive of a beam-type torque wrench while an assistant reads the scale from the other side. You will not see the scale but your assistant who is holding the torque wrench can see it. Use your "3-finger" approach and ask your assistant what the actual torque values are. If you do this several times, you will get some idea of your level of consistency.
Then, to "recalibrate" your "3 finger" approach, set a click-type torque wrench to the 16.5 ft/lb spec and again use a wrench to turn the square drive until the wrench clicks, indicating that the torque spec has been reached. If you do that now and then, you can recalibrate your feel and improve your consistency.
It was these tests that convinced me to use a torque wrench for any important fastener.
Good luck.