From what I could tell, most of the levels were designed in a way that you either have to interact only with a single block or there's another block that may be easily used to set the magnet's direction. This works well in most cases, however, I ran into some issues in level 8...
In my particular solution for that level, I had to push a block downard, but trying to activate the magnet would attach it to the wrong block. After a lot of trial-and-error, I did succeed, however I was quite confused about how the game decides the direction in which the magnet will turn.
After testing it, I got these two different results for the same apparent "command":
Simply activating the magnet before of after the movement changes which block the magnet turns torward. This isn't ever clearly explained by any level (at the very least, I was able to complete every other level without fully understanding this).
It gives a somewhat "random" and uncontrolable feel to the game, which is quite undesireable in a puzzle... I don't know whether allowing the player to manually set the magnet's direction would be a good idea; the game seems to have been designed around this restriction. However, it seemed troubling in this particular level...