There is a world of difference between what is taught as CRM (don't be frightened to be assertive - speak up - ask questions - seek several opinions - suggest politely - use certain planned phrases like "Captain you are too low - we MUST climb etc"
AND
Flight deck etiquette. Such as not snapping at the other pilot when he is attempting to assert himself. On the other hand, asserting oneself to the captain in the guise of a "support" call, is often counter-productive in that it arouses ire.
"Supporting" the PF by reaching and placing your hand on the gear lever after lift-off to signify you are on the ball and waiting for his command of gear up. Also known as "hovering".
"Supporting" the PF by casually holding the finger on the heading select knob waiting for the command "set heading 180 etc"
"Supporting" the PF by placing your hand behind the throttles as he pushes them forward to take off power and at the same time actually pushing the throttles under the PF's hand when the PF is attempting to make a smooth application of take off power. Now that is really annoying.
"Supporting" the PF by riding the rudder pedals during the PF's take off and landing run and especially nearing rotation, sliding both hands very subtly under the control wheel to "assist" his rotation in case he forgets to rotate.
"Supporting" the PF by changing navaid frequencies even though he has not asked for them but you think it is a good idea at the time. All done in a non-threatening manner of course - but in fact these are not "support" actions. They are done by individuals who just can't keep their grubby hands of knobs and levers because they see themselves as a member of the team up front and feel the urge to be seen as on the ball.
There is an art to keeping opinions and hands to yourself lest you be labelled as a fly-by-mouth personality and allow "support" calls to become an excuse for back seat driving.
CRM and Cockpit Etiquette are different birds. Airline induction courses stress CRM usage. Yet, for such an important human factors subject, rarely is cockpit etiquette discussed in the class room as a specfic subject on its own. It needs to be.