loadMacros() calls in a macro file (for example, the PGstandard.pl file is just a file that loads a bunch of other macro files).Remember, however, that macro files have to be compiled every time the problem is viewed, and that means every time a student submits an answer as well, so loading extra macros files that aren't needed is inefficient and slows down the processing of every problem for every student.
It also makes it harder to share your problems, as you need to share your super-macro file as well.
For these reasons, I don't recommend including macros that aren't needed in the problem.