From: (Mike=A0Connor)

If you want an absolutely top expert=B4s opinion, then see here;
http://www.sexyloops.co.uk/cgi-bin/t...D4cafde435435=
6c66aecbb69c86a7b78c;act=3DST;f=3D3;t=3D195
For casts of less than about sixty feet or so, no wrist is needed. It
can be used, but it will introduce faults if not done properly. Simply
allowing it to "break" will always introduce faults, and may cause pain
as well.
For simple "pick up and lay down" casts, only rotational power
application is required. ( The rod simply travels through an arc).This
is easier with a locked wrist. For long casts, then the stroke length
needs to increase. There are several ways of doing this.
For maximum power, a "wrist snap", as described above is also required.
As hardly anybody needs to cast 90 feet or more with a #5 wt, there is
usually no call for it under normal fishing conditions.
If you use light gear, and understand the mechanics involved, you can
cast using practically only your wrist. This is however rarely a good
idea for most people. Wrist muscles are weak in comparison to shoulder
muscles. This may also cause you various problems and pain.

Hi Mike, thanks for the link and excellent advice. It seems that many
of the experts have differing opinions regarding the use of the wrist in
even the basic "pick up and lay down". Joan Wulff is a notable example.
She teaches loading move, power snap of the wrist and then drift to 12
o'clock on the back cast. Then loading move, power snap of the wrist
and then drift to the target on the forward cast.