If you set up rules 1, 2, 3
and you don't make them dependent on each other, then they don't bump as long as it's not referring to rule X or Y. They will still perform their task.
"Run Rule Actions" skips the triggers and goes directly to the "Actions" section of the specified rule, if that's what you're asking.
This is really the only way that would make sense, if it helps to remember it that way. Triggers are events; they do not have truth values and therefore cannot be "evaluated" in that sense. "Run Rule Actions" is basically a way to trigger the specified rule in addition to whatever triggers (if any; they are optional, though without them this is probably the only way you'd be able to make use of that rule) you have specified.