Despite being put off from EK for life I still envisage the airline will have pretty high standards for upgrades. Not everyone will be suitable and therefore will never see a command course. Others will fail somewhere down the line and return to the right seat. Same applies to DECs. I know of at least one guy who failed the DEC OCC course at EK.
There's always that factor. Get a succession of poor DECs and it throws a major swerve ball. I also consider the whole 'fast track' process in any operator to be complete BS. It's at the wim of managers and members of the hit parade. It also instils an element of entitlement among the ranks. A command should be earned, which I know is sometimes complete bollox as well.