When I was involved with the calibration department of a major aerospace
contractor, it was demonstrated that the 'click' type wrench was completely
unreliable.  This included the hi dollar ones from Snap-On.  If it's accuracy
that you're after, you can't beat the old beam type.  They're usually within
about 3%.  A dial type that is not regularly calibrated can be trusted to get
you within about 15%. Save the clicker for torquing Chevy/Ford head bolts.  We
used dial types on a 30 day calibration cycle.  I use a clicker for lug nuts
and a beam for engine assembly.  I've got a couple of in/lb dial types that I
use for low torque values.  And, before you ask, no, they're not calibrated
any longer.  Check them against a relatively unused beam is the best I can do.

A couple of things that one can do to improve the accuracy are to 1.) ALWAYS
set your 'clicker' to 0 when you're done with it.  2.) NEVER use it to remove
fasteners.  It ain't a breaker bar! and 3.) try to have a selection of
different wrenches so that you're using a wrench in the mid-range of its capacity.

Jim Arnott
WetWesties
Union, OR