Years back we had Nick Dyslin (Kakatat rep) speak at our kayak club and demo seal replacement and he advised the stretching. If you have a football player neck and a small neck seal than you might have to trim it. I find they are always tight when first installed or new (I always buy ex. large replacements) and the stretching does the job. I'm not a big person and even my wrist and ankle seals are pretty tight when new. I seen new ones go after a cutting job - granted maybe they did a sloppy job, but you do take a chance when trimming them. I think 100% of all seals are tight on the users - especially when new. I know paddlers who just can't wear one they find it so bothering. I don't think Kokatat assumes that 100% of the users are trimming the neck seals. Just like an elastic band, they loosten up with use and/or a bit of stretching.

I find after two years, the outer edge gets a bit weak from the sun and use. I like having extra material because I can trim that off if I want and bring it back to a fresh edge.