well i have made a ton of bubble, ( literaly) and i can say that the highest i've realy ever seen return is just over 10%. I remember back in the day bog was saying he got 18%, but was weighing his bubble wet, so that didnt count. A very small amount of water present in the final product can confuse ratio's.
I have gotten as little as 2% of fan leaf return and as high as 10% for fine trim, that does not include bud at all> I have run tons of bud as well, but never get more than 10% return even with bud. I think the process is realy about getting WHAT IS THERE. as the ratio's can and will change depending on strain, growing conditions, and about a million other factors.
Just my two cents.
the whole process is just much more fun, when you focus on the QUALITY that you get, and not the QUANTITY.