I rotate my own wheels rather than have them (almost always) overtightened by the air wrench at the dealer/tire shop. Overtightening, or uneven tightening, can warp a rotor. Undertightening has obvious other concerns.
A good torque wrench will last almost indefinetly.
I read somewhere that graphite - found in "Lock-EZ" for example - applied to the studs will reduce the chance of the fastener seizing.