Akainu almost lost in two shots against Whitebeard, and King lost in what, 2-3 shots against Zoro?
Endurance is the ability to take punishment and keep on going. Doesn't matter how much of an initial attack you can withstand, if you can't continue to last that long afterwards.
Granted Katakuri wasn't so much endurance testing, as he dodged most of the attacks until the very end, but even so, he still managed to withstand a half hour worth of Snakeman attacks, after exhausting his stamina over the course of 10 hours.