does it make sense to just have one celeb site with all celebs or different websites with different domain names to each. which makes the most adsense money.

This is one of those questions that has so many variables there isn't one answer.

Variables:
How will you attract traffic?
How much content?
Where are you getting your content?
What do the ads pay?
And more.

You can "Park" a domain undeveloped with advertising all over it hoping for type-in traffic. Sure this is a small amount of traffic, but with hundreds of parked domains this can add up.

Also you can sell the names you horde for a profit.

Personally this seems to be harder, more time consuming then just simply writing a good site or two, tune em up, white hat and dedication. Less workload then managing all those empty sites (cause you need LOTS and LOTS of them to make it worthwhile.).

A good example that this is not a good strat is to look at ebay. You see giant blocks of domain names for sale all the time from folks trying to get OUT of this business model.