The funny thing is that the more you use a torque wrench the more tuned your memory and muscles get and the less you find you need it. Regular mechanics do it often enough that they know how much to torque most stuff by feel. But they also know enough to use a torque wrench on the really fussy stuff. This also assumes that they are doing it regularly so they maintain the feel.

For new or infrequent home mechanics it's not a bad idea at all to get one and use it regularly when in doubt.