This really depends on what kind of photographer you are. There really is no set number of photographs you should be able to take per hour. Instead, it all comes down to the quality of the photos you take. If you take, say, 200 photos in a set, and only 67 of them are worth paying for, well, the client will have felt that they just wasted money on 133 photographs they can’t use - especially if you charge by the set instead of a total number of final, usable photographs.
However, if you charge per usable photograph, you’re going to make sure you take 100 photos that are worth saving in the same amount of time the one who charges by set took 200.