What do you mean is he landing it? Yes he lands it? It's a combination of scoring points and wanting to soften up his opponents mid section.
the one where judah countered and dropped floyd? yeh he does it to score some points and to look for an opening. It's better then just waiting for an opening.
He does land it and it worked brilliantly against Corrales and Hatton. It sets up the over hand right and it's a good shot to feint and mix in jabs to the head and check hooks. It's a dangerous punch to throw because it opens you for the counter right but Floyd is so quick that doesn't matter!
If he lands a jab to the body he can pretty much land a right hand on top easy. As stated it doesn't cause the same damage as it did against fighters at 140 and below.
Its the easiest punch to land, fighters today dont use it nearly enough. For instance Wlad fights leaning back, that punch would be easy to land on him especially since he isnt a counter puncher.
I don't think it does much damage, but scores points and disrupts opponents offence. He is brilliant at it.
Like george foreman said in one of his(mayweathers) fights "a good jab to the stomach is like stabbing a syringe in the pit of the stomach"
Disrupts the rhythm of the opponent's offense and takes the wind out of 'em. Fast punch. Simple as that.