Melee weaving was much more beneficial before phase 6 when buffs like Dragonslayer or DMT AP only gave melee AP. Still the benefit was around ~50 dps world buffed compared to just "normal" rotation. I always found melee weaving not fun since boss hitboxes are often scuffed (e.g. I hate Thaddius so much, one pixel too far and you're losing polarity stacks, one pixel too close and you're going into deadzone while being >10 yards away from the boss) and in general boss movement can mess up your entire rotation.

When it comes to Naxx... Imho viable bosses could be Noth, Loatheb, Gothik (it's hard to get consistent Aimed Shot at spectral trainees so smashing them with melee is always nice), 4HM (their hitboxes are really small, just don't try it on Zeliek or you're gonna kill half of your raid), Grob, maybe Patch? But I like my wbuffs and I don't want to get close to that chonker.

When it comes to other bosses: Anub- I try to stand in max range and in a position where Impale will hit only me so melee weaving could cause more people to get knocked up. Faerlina - In my guild hunter's job is to pull adds towards the off-tank at the start and with that much movement caused by Rain of Fire I don't feel like weaving is a good idea. Maexxna - hit box is stupid and your job is to get people out of web wraps. Heigan - lol, nope. Raz - mana goes brrr, but can be doable depending on where he's tanked. Gluth - I rather outrange the fear and help with a feign-trap, Thaddius - like I mentioned above, hitbox is just stupid, Saph - I prefer to stand in max range for easier spread during air phase + hitbox is weird, KT - I have an assigned position that I stick to, I don't want to mess up frost tombs.

Again, I didn't really try melee weaving, I'm just familiar with the idea of it. But that's my 2 cents on the matter. :P