The Problem With a Fact-Checker in a Debate

So you build up this drama of a 90-minute debate.  Figure in the 16 minutes that the moderators will take up, and divide the remaining 74 minutes among two folks....equaling roughly 37 minutes each.

First, there would have to be two fact-checkers...something that Joe Biden and the press will not agree upon.  I'm pretty sure that Joe and the press will say one single fact-checker will be enough.

Second, as the individual goes into the commentary....it'll be at least two minutes before he says something that might be semi-true or mostly false.  How do you work this as a fact-check, with the guy ending his commentary in less than sixty additional seconds?

Third, will the fact-checker be correct?  Will we need a fact-checker to the fact-checker?

Fourth and final.....what if the commentary of the fact-checker is totally wrong? 

For some reason, I don't see this lasting long.  The networks running this on their own?  Maybe, but it'll create more skeptical views of the whole mess.