have you watched bernies youtube vids? i really liked his vid on how to cut up a roo for lace and then stretch it prior to cutting for width....i always cut wider, about an inch id say, then stretch then cut several strands out of it as that creates less waste. i do agree on the splitting, needs to be done...i posted a link a while back for a little wooden splitter, its not hard to make, works great for roo and just uses utility knife blades.
in this vid bernie says he wants to end with 6mm strands so he cuts them at 8 mm then stretches and by the time he bevels it he is down to the size he wants.