In my opinion, there should be no exit polling and no reporting of results until ALL counties have reported and been certified. There is a nationwide tradition of Dem-heavy counties waiting till they are dead last to see if they can manufacture enough votes for victory.
They always do that in close races. I have been in/following politics for going on 50 years and the first time I remember this happening was in '60 when the Nixon-Kennedy contest. Kennedy's people kept calling Chicago and asking Daly about Cook Co., which, naturally, hadn't finished reporting yet. He kept telling them he "guaranteed" they'd have enough votes to put Kennedy over. Guaranteed? Cripes, the guy is practically advertising his fraud. Same in WA state in '04 with the governor's race. It's already happened this year in OR. It's happening as we speak in MN.
It should be a law that cities have to report first. If they don't, then no results reported until everything had been sent in to the Sec. of State, and then release all results at once. None of this "late reporting" crap.