Too much nitrogen can kill or reduce crops, when a fig tree wants to grow too tall in a year I prune it's height a little to force it to grow more under the cut, which makes a wider trunk and branches, I have never had any plant besides fig trees grow too tall to fast, yet pomegranates when they get older can grow too fast, mine are too young too do that. I make a 0-18-8.6 fertilizer and use that whenever nitrogen is not a good idea, fruit and vegetation are better quality and in higher numbers when the two other fertilizer elements are still in the soil. I have been experimenting using the fertilizer with different types of plants yet no ripe fruit yet and I have not been applying often enough so only time can tell. Pear trees are not strong enough to grow that fast. I do not have much experience pruning pears yet, yet I do not find that heavy pruning makes our pear tree need more pruning later, then again ours never grew anywhere near as fast as yours is, that is scary fast for a pear I think, at least a young pear tree anyway. Same thing with fig trees I do not find I have to prune more often when I heavily prune our fig trees either with one exception, if they are growing too slow, then they may come back much faster than the snail going uphill pace the trees had before. Still not too fast though.