So perhaps this issue is that I was making a distinction between "receive movement points, spend movement points, then receive and spend more movement points" and "receive movement points, receive more movement points, spend all movement points." If the latter is not interrupting a movement action (performing another action after the receiving, but before the spending of some movement points,) then what constitutes "interrupting" a move action? I think we have to assume that "interrupting a move action" means performing another action before all movement points received from a move action are spent. In the special case where this "interrupting" action is another move action, the FAQ seems to state that there is no need to distinguish the movement points received from each individual action.
The rules regarding "move actions" are a bit weird in Descent and large monsters just compound things. If it wasn't for the large monsters shrinking/expanding (which I do feel is a necessary evil in a world with smaller, more constrained maps), they probably could've left out the "interrupt a move action" and just left a "move action" as giving you points which you could spend later in the turn. But they needed some way to limit the shrinking / expanding possibilities. (Also some exceptions for "enter a space during a move action" cards which I think could've changed without much effect.)
That said, the case of the rules stating "use two move actions simultaneously to receive double movement points" is effectively the same as "declare a move action, shrink, interrupt move action and expand in the same spaces as you started and declare a second move action, shrink, move double your speed, expand at the end".
It drives my playmates crazy esp. w/ 4-6 space monsters who only have 3 movement but are able to descend on them in 2 move actions.
Yeah, the Speed of 3 is deceptive with Large monsters, but this is very definitely intended. If you look at comparable large monsters from 1e, the 2e versions almost always have a lower speed because it is meant to take the shrinking/expanding rules into account.
Edited by griton, 05 May 2014 - 09:34 AM.