Tobacco is too expensive here to waste a thing.
I've not ever found 'twigs' [which would be tossed] but veins are chopped with scissors and tossed back into the jar.
I don't even look. If a stem or something pops up and proves to be difficult when loading a bowl, I pull it out and throw it away. Otherwise, if it's in the tin, it gets smoked.
Everyone takes their favourite bit of sticky stick they found in the mix that month down to the next meet and a series of elimination style poohsticks is played out in a soup bowl half filled with water to find that months winner!