This leads to the question if some gladiator fights may have been partially "staged". In other words, if the gladiators were instructed to "fight" for a set amount of time before actually trying to kill one another. Gladiator fights were a form of entertainment after all, how entertaining is it to watch a 30 second fight?

Follow up question, is it true that deaths were very rare in the arena? I'd imagine it would be far too costly to continue training new fighters if they died quickly, so is the plethora of deaths a Hollywood creation?

We have a small idea on how long the fights went on for. Since we have ads for Games that have survived. For example in Pompeii we see the following add

"A hunt, and twenty pairs of gladiators belonging to Marcus Tullius will fight at Pompeii on November 4-7." CIL IV.3.4 #9979)

So 20 fights took 4 days along with a hunt. So the idea appears to be that they would take quite a while. 5 fights a day for four days would indicate that around half an hour would be the expected length obviously some would be shorter others would be longer. There are many fascinating little facts about the games. One of my favourites is a tombstone in Turkey which has a gladiator complaining about his opponent cheating.

Roland Auguet suggested differing amounts of times for battles which were dependent on which gladiator types were doing the fighting in his book Cruelty and Civilization: The Roman Games. Among the longest lasting were the battles between the Andabates type of gladiator, who were fully armored and essentially blind in their full-visored helmets. They would essentially echolocate to try to find their opponent and then try to strike at the joints in the armor. Auguet suggests most of these battles ended due to exhaustion rather than a particularly well-struck blow.

Would it be fair to say that professional gladiators may have been their era's professional wrestlers?

So very skilled and capable of inflicting harm but more likely to put on a show of combat rather than an intent to kill?