Whether a standard is a must or a should shows up only when someone hands you an honorable way out.
An offered exit tests a commitment harder than any obstacle, because a person can take it and keep their self-image intact, telling themselves they were released rather than that they quit. He stakes his refusal on the life of Yahweh, which puts the standard somewhere he can no longer quietly lower it, and a standard that cannot be lowered stops him from recalculating his odds at every town.
Inheritance follows the standard, not the résumé. A man who accepted the reasonable release offered at Bethel would have gone home an assistant and spent the rest of his life believing the double portion was simply never offered to him.