I've noticed a lot of people commenting on the strategy of waiting to go up, and feeling like this is a flawed test as a result. There are a few factors to consider, though, which are why the B-Rank player did it this way, and would say there is no problem with the test.
Reasons that could be given for plausibility when talking to other test administrators:
1. All eyes are on the stage, which means that people could potentially get incapacitated while "waiting" without anybody seeing who did it to them. As such, you could find yourself attacked by many more contestants if you wait.
2. If others are also trying to wait, you could get thrown up onto the stage by a group of them, so that they can wait longer, which could put you off balance if they throw you close to somebody on stage, and you could be knocked off before getting to do much.
AND THE ACTUAL REASON:
3. The Proctor has stated that he doesn't think any of these people are worthy. So it isn't about finding the "most worthy" it is just about limiting the number of "unworthy" people that "pass" to 5. He could have just as easily looked at them to "evaluate" them, and just picked 5 at random to say they are the ones that passed. He thinks they are all trash, so he doesn't care whether the 5 are the "best 5" from the group or not, and this form of picking is to show just how little he cares about how they compare to each other.