Discussing camshafts is almost impossible, there are way too many variables to give any sort of half decent explanation.
Basically a cam has two main functions, one is "lift" which is how far it opens the valve and the other is "duration" which is how long the valve is open for.
Just when the cam should start opening the valve and when it should close it is effected by many variables and engineers have been discussing and argueing over this since the first engine was invented.
To have an understanding of how all the variables effect each other takes many years of engineering study and at the end of the day there is no "perfect" set up, everything is a compromise.
In your post you refer to the piston having a bigger bang, that also is another area that can create much discussion. A lot think the spark ignites the fuel and there is an explosion, that is not actually correct. The spark does ignite the fuel but it doesnt cause an explosion, it sets fire to the fuel mixture and how long it burns for and what temperature it creates is a whole new discussion.
