When I decided I wanted to learn to sharpen my own knives, I was overwhelmed by the sheer volume of sharpening supplies and in my ignorance at the time, I thought I needed everything I could get my hands on, the more I had the sharper the knives would be. That was a mistake. Today, I rely on just a handful of good products, I use them every single day of the week.
Now you may wonder, if a finer stone produces a better cutting edge why do I need a coarse stone at all? The answer is that finer stones work much more slowly than coarse ones. The amount of metal a fine stone removes with each pass is much less than what a coarse stone removes. If you have an edge with a good shape to it from a coarse stone, this is not a problem because the fine stone doesn’t have to remove much metal to improve the edge. If the edge is dull, it will take many times longer to reshape it with a fine stone than it would with a coarse one.