This is only partly true, and only in certain circumstances. Good LaTeX style depends on several things, but normally one tries for three things: 1. portability, 2. logical mark-up and 3. readability/editability.
Package use can affect portability, so one should normaly eliminate any that are not absolutely needed. A journal may send back a submission that fails because they don't have a particular package or because they have a different version. Often they will not debug to find out which package is at fault and ask you to omit them all!
Logical mark-up almosts requires making ones own commands. It is much better to define a macro with a name that reflects the reason for the \qquad\textnormal{...}
than to have to repeat such a sequence often.
Readability is also improved with a well-chosen macro name, but editability is not. An editor may want to change that \qquad
of space, but has to constantly go back to the preamble and read through the definitions to know which macro to edit. And if the author's mark-up is inconsistent (same command for spaces in different contexts), the editor may have to find every occurrence and change them to different size spaces.
Logical mark-up sometimes has to be balanced with editability. While it is easy to edit \qquad
down to \quad
, it may be harder to read your special command and deduce that that is what needs to be to changed. After many years of trying to get my papers to look as nice as possible, I now keep new commands to a minimum. Mostly only \newtheorem
s (because none are defined by default) and the few \DeclareMathOperator
s that LaTeX and amsmath
neglected to supply. I use \documentclass{article}
and load just a few packages, sometimes only amsmath
. (Of course, if I self-publish a document for my own use, I go wild.)
I have seen many papers with hundreds of macros, most of then simply indecipherable shortcuts for some much more readable combination of commands, many never even used. Such things are a nightmare to edit. One appreciates why an editor or professor would not want to see that, and why a journal might include instructions (as many do) to write the paper "without any user-defined commands".
Your professor has probably seen many such instructions and jumped to the conclusion that it is "good style". Still, you should try to keep him happy. You might start by asking whether you need to have so many \qquad\textnormal
and if some other approach might be better. In the event that you must have them, it should be trivial to turn all your single commands into this expanded version with global search-and-replace in your text editor.