It really sounds like you are doing something wrong.It's not worth it when you are looking for deep core asteroids for a few hours. And made almost no money. That is not worth it at all,
That is the only way to explain your failure to find the right asteroids.
Please watch a few Youtube tutorials. There are also a few with tips and tricks.
I promise you will get better at it, and before you know it you will not even be able to remember what you complained about.