How full is TOO full?

I read the thread about changing the fluid in the new sealed auto transmissions. All that concern with making sure the level is just perfect...

First, things that give me reason to think: even the old trannies with dipsticks you checked it warm, but there was still a 'range' with FULL and ADD, so it didn't have to be precise.

Second: several posts have suggested even factory fill isn't very accurate: a couple people opened the check port and fluid pours out (not dribble per spec) even though it was cold so it didn't have a chance to expand volume! Others adding almost a quart (I think one guy said the dealer added 2 qts at a service) to get it to a dribble out when it's hot.

That makes me wonder just how accurate the level really has to be. I was thinking of (when I do my partial drain and fill) just let it sit overnight (so it's cold) and drain, then fill and operate for about 15 minutes as in the post, then open to let the excess drain to a dribble per spec. I bet it'll be closer than many factory fills if the above is a standard.

Any thoughts??