Maybe, maybe not. I did 10 of the 13 hours at the Womens / Nationals last month. I'll ask those of you who were listening [sadly, it's lost, we can't replay it now], was I still good the last couple of hours? I know I've done long stints other times, I think Karl and Johnny did so at INDISC one year, and some other folks here have as well. Anybody remember long broadcasts that you thought stayed fresh the whole time?
I'll add one other note. In Texas, while I was there most of the time, the other one or two people on air with me swapped out more often, e.g. like your two hour stints. Levi, Colin, Priyanka and many others sat in for a while. I know in some sports, that's how they work - - one or at most two "lead" announcers for continuity, others who come and go for variety. That's how I'd set it up if I was going to plan it in advance. At PAPA, you could have a non-qualifier (player perspective) plus a PAPA HQ-type or second player as the continuity people and players who got byes (round 1) or who just got knocked out (rounds 2-finals), or others if those people aren't interested, as your rotating announcers.