I’m going to discuss what benefits planetary magick have, which are really good. In reality it can be seen as one great asset, which is that as a magician, one can count on a celestial body for “sending” one a spirit that is the most suited for the task at hand. I have demonstrated and written about notable examples in my previous articles, e.g. on The Sun, Venus and so on.
Even if one were to work and call down or absorb planetary energies, that is how they’d work in most cases. The only exception, in which I have extensive experience, is planetary magick via the Greater ritual of the Hexagram. Alas, it has no real practical benefit, since you only absorb the energy of a planet or zodiac sign and the ritual takes a while too (30 minutes min.)
As mentioned before, asking or petitioning a planet for a spirit that specializes in a certain matter is an excellent option, if you can’t find one that does so or don’t know one.
Example is that if you wanted someone for becoming a musician, Venus would be able to send you someone that’s perfect, since Venus deals with artforms; much better than wading through workbooks or grimoires looking for one that might not even be adept at that.