Blunt rolling is an art. It must be excuted with skill and precision, which can only come from a combination of practice and natural born talent.
If a blunt is too tight, the weed will burn quickly with only a limited amount of smoke being able to pass through.
If a blunt is too loose, it will burn too fast and fall apart. The former and latter both wasting weed.
A perfect blunt allows for a nice, strong hit, without burning too much bud at once, and without falling apart while the puff-puff-pass, takes place.
Weed wasting also applies to improper packing of bowls and slides. Yet again, it can't be too tight or too loose.
Cheap glass pieces also may be called weed wasters.
Helpful hint: If you can't roll, let a buddy help you out and save practicing for home. There's no shame in making sure your weed yields its maximum potential.
"Straight, but I'm rolling."
"Awh man I really wanted to do it. I've gotten better since last time, just let me show you."
"The fuck you will, not with my bud. We don't allow weed wasters in this house."
Damn, Robert is such a weed waster. Don't let him pack that shit next time.