Thanks @twentyseventy, for just pointing me to read the first few pages (I was just being lazy to ask for the ELI5 ). It's a bit tricky to get into it and all the calculations but I think I get it, or at least most of it. I did some calculations myself and as said before this is very interesting stuff. Even if you don't speculate on the difficulty, but just keeping an eye on the numbers and calculate what is more profitable. Definitely have a go/play at this. Cheers!