I think the answer is yeah, but no, but yeah...They would try to keep a reasonably even layer of sapwood, so if the sap wood is thin, just leave it as it is. IF it is thick it would need thining down at the tips of the bow (else they would end up being all sapwood!), maybe they'd thin it down over the whole bow, but I don't think they'd slavishly 'follow a ring' but obviously they'd use the rings as a guide.
If the bows were being made commercially for the armies of the state they would be make them quickly and wouldn't be worrying about the niceties. Doubtless archers would also fettle their own 'standard issue' bows.
If you had to make a dozen Yew bows per day (or whatever it was) how fussy would you be?
Out of interest on my own Yew Longbow it follows the outermost growth ring for the most part, but near the tips where there is some twist and too much sapwood I've cut in a bit, there is no sign of lifting fibres tho'
So it's a definite maybe!
Del