full swing an extension.of.pitch.shot

I would strongly disagree. Extension of a chip shot? Yes. Pitch, no, not at all.

With a pitch shot you are using bounce and sorta/kinda flipping at impact which is intentionally almost fat, the bounce will cause the club to glide into and under the ball.

A chip is striking the ball with a sharp downwards blow with the leading edge striking the turf after the ball, I would say that this is a smaller version of the full swing. It also has significant forward shaft lean which is essential to the full swing.

I spent a lot of time last season working on my chipping and getting my swing bottom more forward, the result was much crisper chips with a lovely little clean clicking sound, this transferred very well to the full swing and  I saw a lot of improvement there even though my practice sessions were much more focused on chipping.

I find pitching to be very closely related to bunker shots, both of which (at least the way I play them) are kind of the anti-thesis of what you want to do in the full swing.

Short version:

Chip and full swing>>leading edge strikes down and into turf after ball, lead wrist very firm.

Pitch and sand>>turf/sand contact is all bounce and prior to ball, wrist breaks down or releases thru impact.

I'm sure some much better players will be along shortly to refine what I have said here, perhaps maybe even make some corrections but I'm pretty sure I've got this part down pretty well.

Relaxing is always a good thing IMO. You don't necessarily need to know what's happening mechanically to make a good shot.