How do you approach the situation in which a pattern prescripes a high kick that a student finds challenging? You could argue that it's better to do a good kick at a lower height rather than a mediocre one at high level. However, the actual formal requirement of the pattern is head level, and postponing this might work against you, and passing him or her might be talking the short cut in their development. I personally would not allow the person to be graded unless he or she can reach jaw level, since that is what the pattern states and ones own jaw level does not take unreasonable flexibility. I talked to a 4th dan who took the first approach but to me this negates the hole point of personal development in martial arts. You are suposed to push yourself past what you used to be able to do!