And it can be stuck on like you wouldn't believe. Last one I did, I had the bike upright, with the owner sitting on the rack and a cheater bar taller than myself. I had the rear wheel off the ground - but not his feet - before it finally broke free.
And there have been several stories here about people using the vise method turning/toppling work benches, or breaking them loose when fighting stubborn BBs.
One shop here, the mechs take pride in not having to ask for help with BBs. Their biggest bench isn't bolted down, so when something stubborn is encountered, the unlucky mech has to ask the rest of the staff to come and sit on the bench for extra ballast. And it costs the mech responsible for the bike a beer for each person he needs as ballast...

On the subject, has anyone ever managed to destroy a frame while removing a stuck BB?
Is it structurally possible to warp the frame before the threads strip?
Or will the tool flats/splines go first?