Is it typical that it works for some folks and not for others.
It just takes practice. I've seen guys hold down too, and they'll move when gravity says they shouldn't, but i like them sticking out straight in front of you because it's more sensitive imo. Just keep playing with it, and it helps if you can do a site that they've located on so you know where all the stuff is. And again, for most applications witching is just an additional aid, and can't replace the other types of locating tools and equipment, and other things to stack the deck in your favor like more and more cribbing or soil probing. And yes you need a dig permit if you're going to probe, you can easily poke through a gas line or something.
When you call in a locate the guys go out there and hook up a power source to the utility and use a tool to pinpoint it. If it's plastic they bury a wire to carry the current, and all connections are made in waterproof boxes to ensure reliability, in other words you really don't wanna have that fail because that's what will be used when digging it up. Even with all that it's a 3 foot on either side window, and it's often only 18" under ground. With smarter and bigger stuff in the ground, say like a directional drill, it's insane how well they can plot it, and can curve it around to go exactly where they want. But that's because they can change frequencies, have a far more advanced sensor placed directly on the ground, etc.
If you're trying to find something unmarked, the material makes a huge difference. If it's steel you can use locating equipment, even a compass can help. If you're going to be using a crane it only makes sense to learn about what's in the ground, and getting a dig permit so you can simply probe the ground can tell you tons of info. If you've ever seen guys prepare for a concrete pour on a commercial job you'll likely have seen a random guy walk up, put some instrument thing on the ground, and then drive a spike on the tool into the ground with a sledge. He's measuring how compacted the base is to make sure it's up to specs, and a probe can tell you the same thing with tactical feedback. You'll know if you're hitting rock and stuff, which tends to stabilize the soil. If it's a tank or pipe it'll have sand all around it, easy to feel with a probe too. Foundations often have pea gravel, very distinctive with a probe as well.