For some, I bet they were!
JD, now you're just being silly
Of course they wouldn't hand out bows they weren't sure would hold.
But give anyone a full year worth of good yew staves and a piecework contract, and I bet he or she would be able to make a fully functioning warbow without having it on the tiller, in the end of the year. And that's probably what it was all about - making effective weapons as efficiently as possible.
Though, I don't think you can attribute much to the fact that most of MR-bows didn't have stringfollow. After 450 years, the wood would probably have straightened itself out to near its original shape.
Anyone got an idea of the relative air humidity onboard a wooden ship sailing along the same latitude as England?