On Fri, 24 Sep 2010, Chuck Guzis wrote:
  the technique because of the nature of valve end-caps.
They're
 usually somewhere around 3/4 - 1" in diameter with fine machined
 threads--the danger of cross-threading is great.  However, turning
 the cap anti/counter-clockwise until one hears the "click" ensures
 success.
 I suspect that most plumbers know about this when using fine-thread
 fittings. 
MOST plumbing is a relatively coarse thread.
Screw-mount camera lenses. 39mm x 25 tpi.  (39mm x 1mm is a less than
perfect fit.)