SAS, we do the ground and refresher training (required by JAR-Ops 3) before the Sim sessions for LPC/OPC. This generally covers technical systems, anything new in Ops Manual, CRM, recent incidents etc. What we try to avoid doing is coaching for the LPC/OPC. If a pilot needs intensive coaching prior to his test, that means that he couldn't reach the minimum standard without it. That means that in the days running up to his test, he is incompetent in the role. Not too good for the passengers!
Its a fine balance to combine training and testing, but one must be careful not to coach an incompetent pilot through his checks.