Yeah, Advent mines take a TON of micro, since you have to select the fighter squadron (not easy in a crowded gravwell), make sure the squadron is full (8 fighters), select the location you want them, wait for them to move to that location, then click to activate the minefield.
The squadron then instantly starts being rebuilt by the carrier/hangar, and you do it all over again.
You could let the fighters "turn into" mines automatically, but that's assured frustration.
The benefit to this insane system is that you can fly an entire minefield across any gravwell at strike craft speed, then instantly dump them on a hapless enemy. (Although they do have a slight activation time between fighter/mine.)