Jungle Question

I generally main jungle. I've seen people complain about the "we lost because we got no ganks" gripe before, but I'm wondering how many people see, and have a problem with, the "you should know I was low on X"

Put another way, as jungle, I'll see a lane is being pushed to the tower. I get over there, I get in position, I make sure everything I need (mana, ability, Summoner) is ready to go. If that's the case, and I think all the conditions are right I'll G ping the champ I want to gank. Prior to this, on the way to that lane, I'll type "Coming bot" (or wherever) and use the "on the way ping."

Rarely does anyone flag me off. And occasionally when I go in for the gank, the ally runs behind the tower and Recalls. Invariably, I ask why they left.

"No mana"

"well, look dude, just please V-ping me off, I'm taking a lot of variables into account and I'm not looking at your bar"

"A good jungle would."

Questions:

Is it accurate to say a good jungler would look, even with all that notice given to the lane? And if so, how do you as the jungle determine when a bar is high or low enough? Always health or do you look at the resource bar, too?

If that's the norm, I'm fine to adapt, but I feel like I'm managing a ton of things in the game and that having to manage a laners bar in addition is just laziness. I mean to say, if my job is also to watch your bars, then what is it that you're doing?