Is it absolutely necessary for my kittens to wear an E collar?

I have two kittens, Simba and Nala (Male and Female, respectively). They've both been neutered and spayed yesterday and wear these ridiculous E collars. They hate it and often make a mess of things by bumping into walls, household objects, and have trouble digging in their litterbox (and make a mess of that too!) I was curious to know what the recovery timeline was for both male and female, and my vet recommended that I keep the E collar on for 14 days, I honestly think that is much too long, and am considering letting the E collar go after 5-7 days. Can someone help me please? =( any information and elaboration would be perfect. thank you so much!