Lots.
Attitude Era style. Makes the show more unpredictable and entertaining.
I totally disagree. The titles are not as important when they switch hands hands all the time, a new champion is not a big deal, and so ratings, fan interest, etc sour because the titles have no stability, therefore they are worthless. I think Vince Russo proved this.
Still, this question is hard to answer. Undertaker for example for a variety of reasons has never really had a long, eventful title run but he has had multiple runs (mostly short, 1-2 month range). HHH doesn't have a John Cena like never ending title reign to his credit but most of his runs have lasted 3-6 months, maybe more, and have been very eventful. Cena may have had a better individual reign
(admit it, like him or not he moves lots of merchandise and he was good in matches against Edge, Kurt Angle, and Shawn Michaels) but HHH would get my nod as the better overall champion.
Dusty Rhodes had three reigns but each was exceedingly short. None of them was remarkable for anything other than the fact that he won the belt. He was a great wrestler, one of the best entertainers of all time, but he was not a great champion.
Ultimatley to hold the belt for any length of time many things have to happen, some of them out of a wrestler's control. You can be at the whim of promoters who make irrational decissions (
like when Eric Bischoff had The Giant win the WCW title from Ric Flair because he missed a show in Arkansas, even though Monday Nitro was doing well in the ratings with him as champ, his feud pitting him and Elizabeth against Randy Savage was popular, and he almost never missed shows), injuries play a key role (
Undertaker's last title run ended prematurely due to injury), and you have to have good opponents. No matter how good you are if the fans don't care about who you are facing you will not deliver numbers as champion.
All in all it's hard to hold a major title and defend it on a regular basis for a long period of time. This is much more impressive than short reigns where someone wins one week and loses the next.