Bit of truth in all of the above. Length of wrench does not matter - the scale imprinted on the wrench is based on the length of the wrench. Whether you use a 6 inch or 6 foot, the scaling will be accurate for that wrench. Torque wrenches are calibrated from 20% to 100% of the full range value. They are traditionally more prone to being/staying accurate over the middle of the range. Beam types maintain accuracy longer, I've got one that is 50 years old that is still accurate (I used to calibrate torque wrenches). Clicker (impulse) styles are more prone to lose accuracy over time. On any click-style wrench, lower the torque setting to minimum when finished using it to maintain longevity and accuracy.
Most wrenches have a basic accuracy of ± 4% clockwise, 6% counter-clockwise. Use too big of a wrench, not enough resolution to see fine toque values and over-torque the fastener. Too small - too easy to exceed the torque range of the wrench.
Double Darksider #847
IBA #54767 BB1500+
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