Not true.

Optimal can just as easily be cheaper packs of lower capacity, that can deliver the same or higher amps at a sustained voltage level, and often provide longer duration to boot.

It can go both ways dependant upon the application, and there-in is the problem for newbies. There are many things to consider.

However the basic stuff is much easier than it looks and newbies need not be intimidated by all of the numbers being thrown about.

CGRetired summed it up succintly.