“The enterance exam is not what is important its the fact that they know that after 1 month they will get a bechina”
Should a boy be denied the chance to learn because he can’t do well on a test? Maybe he is not a good test taker. Maybe he is not so smart. Neither of those have any bearing on his learning. If you want to weed out the boys who don’t belong, a better way to do it would be to check who are the ones that are not in the beis medrash when they should be.