For a heeler to be able to deliver a good loop consistently in the right spot takes riding correct position every time. From the back of the box to reading the headers catch and how the steers handling, you need to be able to react and get your horse in the position that brings up your success percentage. Whether or not you get in that spot dictates whether or not you have the opportunity to deliver a good loop every time.
I've taught a lot of roping schools, and have found that when it comes to teaching people how to ride position it's one of the harder parts to master. Every run is different, different kinds of cattle handle differently and headers turn them differently. So every run is different. But the main focus you have to concentrate on is to know right where you want to rope from, and to ride your horse into that position no matter if it happens right around the corner or you have to keep riding and stay patient to get the position you want.
A lot of people give up early, and end up taking a bad shot from an undesirable position. That's why their consistency goes down. You won't always get that good shot on the first hop.