No, that's more of a convenient side effect. Similar actions were built so that similar actions can share partial familiarity. Like going in/out of a facility that's unpowered, so you have to manually crank the airlock.
Similar actions have to manually setup by me. So as a general rule, yes, I tend to make actions for taking identical items be similar, so long as the method for taking them is also the same. E.g. Take Protein Bar should be similar everywhere, but Take Water Bottle and Fill Water Bottle are not.
The 1.2x multiplier of combined actions does stack, for as many times as they are nested.