I cut mine to several different widths, and I cut some 'crosscut' as well.

1/8 is my 'standard', but I like a few in the 3/16 and 1/4 widths too, for larger flies.

I'm not anal about it, I 'measure' the first cut, then use the mark one eyeball to cut the rest. A little variation doesn't hurt what I'm tying....

Buddy