chasing a ring on yew sapwood

[adb]

Hi,
How important is it to chase a ring on the sapwood for making a yew selfbow? I've heard both yay and nay. Is the sapwood not a single growth ring? With very tight growth rings, more than 50/in., how hard is it?
Thanks.

[markinengland]

Chris Boyton has told me that he aims for consistent thickness of yew sapwood, tries not to cut into a growth ring (valley) if he can avoid it but doesn't bother too much about leaving mountains of grain. He thinks it doesn't matter as much as some people think and he is a very experienced bowyer.

[Loki]

adb3112,John Marshall's Christmas Bow doesnt follow the single ring on the sapwood,it looks pretty fine and he hasnt had any problems with it.
Andy