And when you combine it with an initiative modifier based upon % of activity* it makes even more sense to do it the LM way.
* Example: An action that takes 80% action, has a -8 initiative modifier. I like this as it reflects the fact that some actions are more complicated or just take longer to perform. I would also go so far as to say that some weapons take more activity to use than others: flail vs. shortsword comes to mind.