Is it good? Is it bad?

I've seen several brass players start their warm-up routines with some buzzing on just a mouthpiece or on their horns with the main tuning slide removed. This buzzing involves a lot less resistance than is encountered in normal playing, and it seems like a decent way to start a warm-up. So what's to stop a player from removing all resistance and doing some free buzzing? Would buzzing off the mouthpiece affect your embouchure enough to the point that you shouldn't even consider doing it?

The buzzing with a mouthpiece and/or just the leadpipe does remove some resistence but more importantly it removes the restriction of the tube length. Without the length you can play any note which makes the buzzing easier and helps you become more accurate.

I've read a lot about free buzzing being good if only done in small amounts. Most of the anti-free buzzing crowd seems to believe that buzzing without the mouthpiece is bad because without the mouthpiece your lips will function differently. Different muscles will compensate for the lack of the mouthpiece pressure. If that is true then I can see their point. I have been free buzzing for years and I do it often; especially while driving somewhere in the car.

What I like about it is if done with a proper embouchure it is an easy way to warm up, or add to your stamina. However, if you pinch your lips together for support to get a tone then I think it can be a negative thing. I don't think free buzzing has hurt me. I have good stamina and a full 5 octave range. So, done properly it must be good. Done incorrectly it can be disasterous.