Jet2's 737s often have fuel 'issues' on the long bucket-and-spade runs when the winds are stronger than normal. No surprise that they had to squawk en masse this time given the conditions.
So Jet2's fuel policy works over 90% of the time - not bad at all!
There simply isn't enough margin on bucket-and-spede tickets to allow for aircraft to carry an abundance of fuel each trip 'just in case'.