IO540 - the OP has to learn to do it the "manual" way just in case the GPS goes tits up or the signal is jammed.
I do not disagree with your statement
the best navigation tool there is
However, in my tiny cramped cockpit with a mag compass, and a stop watch, I always do it manually and just use the GPS to back things up (show me how good or bad I am)!
I'm not anti GPS at all - I'm just anti unswerving faith in only it.
Stik