I was just thinking today about this. Going back over the years, I've been given some techniques, as I'm sure many here have. And I'm not talking about when one is guided to gradually figuring something out for themselves, I mean when a spiritual being directly relates a method or spell or exercise, or meditation, or whatever.
Because some of what I've recieved works, and works well. And some of it, well, doesn't.
For example, one of the spirits I worked with from the Armadel related to me a way of doing something, by means of an easy way to be put in contact with a much more important Being than oneself whom I will not be naming here. And it works wonders. It does what is advertised in the grimoire, and then some, and in a much more beautiful , perfect way than I would have expected.
On to one that DOES NOT work, when I was doing the Nec Walking, while in the Lunar Sphere, I ran into a Lunar spirit who related to me a simple technique, a word and a hand gesture combined, actually, that is supposed to have a specific effect on anybody you do it to. IT DOESN'T WORK. It never has. Probably never will. Probably won't find out, as I don't plan on walking around trying it constantly after it's failed every single time I've tried to use it.
There have been times where the problem was definitely user error, too. I was given a technique to use, by an angelic being, involving projecting astrally to a certain sphere, gathering energy from there, then descending to another sphere by means of a specific path, and deposting the energy in a certain place there, and this was to be repeated many times for a long time, in order to achieve a certain effect that I wanted. WELL, instead of doing that, my lazy self created a servitor to do it for me. Since it wasn't ME doing it, I didn't reap the benefits.
On a more encouraging note, a Goetic I've worked with in the past gave me a word or two that compel him not only to arrive extremely fast arrival when called, but also compels perfect obedience from him, and can apparently do some other things as well. This one works!
That's some off the top of my head. Generally, in most of my evocations I want a spirit to do something for me, or for somebody else, or whatever. But sometimes I want to learn to do things, both to make life easier and to grow as a magician. The grims don't teach you everything, after all!