Design question: database prefix related

Just wondering if anyone actually uses this parameter in their modules (ie. $DB->prefix). It seems that every module I’ve come across every query written is exp_{table_name}. I would think this prefix should be variable based on settings since it is possible to change on installation.

Anyway, I basically set defined constant at the top of each module file and use that in all my queries. Is that against the coding standard for EE? I’ve read the guidelines and it doesn’t look like it would be.