For me, typically the macro that I base a lot of things are:

/ac ... <mo>
/ac ... <t>
/ac ... <tt>
/ac ... <me>

I almost always have my mouse over the party bars but I keep the mob pretty much targeted.

So this covers everything except for a mob that likes to flip targets and I'm not actively hovering my mouse over a frame.

haven't had any issues yet other than the occasional tank dragging a mob out of my range and NPC healing, which usually means i need to hover the mouse over the tt of the mob I'm highlighting or target it. This isn't something that is all that common.