Just about all of the problems in my calculus textbook range on average range between 4 and 8 steps. Once you know the algorithm the problems are usually easy and routine. It is simply a matter of understanding what the algorithm requires. Ironically the hardest part about math is understanding the vocabulary and the special language that it is written in. As everyone know, all math builds on other math. I have a feeling that higher math problems will continue to range between 4 and 8 steps, it's just a matter learning all the algorithms and learning all the prerequisite math. Is this true? Adding new knowledge to math, that of course is hard, but learning something else that someone has discovered is easy. To illustrate this is easy. Think of how easy it is to understand that F = MA, yet it took centuries for man to discover.