Consider it more in terms like the effort it takes. I’ve just checked the rule book again and the description is very… “rule bookish”… if you catch my drift. I remembered where i got that phrasing from. Shadowrun 3rd.
Free Actions are relatively simple, nearly automatic
actions that require little or no effort to accomplish. Examples
are saying a word, dropping an object, dropping prone, or
casually looking at something.
A Simple Action is one step more complicated than a Free
Action, and requires a bit more concentration to attempt. Only
a few require a Success Test to accomplish, however. Simple
Actions can only be taken on a character’s Combat Phase.
A Free Action may be taken in place of a Simple Action.
A Complex Action requires the most intense concentration of all the possible action types. Only one Complex Action
is possible per Combat Phase. A character who wishes to take
a Complex Action may also take a Free Action that Combat
Phase, but may not take Simple Actions.
While those aren’t identical, the wording helped me to put the MC actions into context. After the first few sessions my group uses those terms very rarely. It get’s pretty intuitive, what you can do within the “round”, depending on the actual scene you are playing. I think i’ts only important to get the pacing right, that everyone get’s equal opportunity and the round doesn’t get bogged down by single turn’s!