I realized it on my second character. I started with Zero and stuck to the legendary class mod once i found it. I began playing with Gaige next and found the legendary mod too restricting. I switched to the zapper, catalyst, etc and found them much more fitting to my playstyle. Now all my characters are using purple mods and the legendaries are in my safe.
Each of my characters has around 4 class mods on their loadouts. Their usage is dependent upon the situation. My Sal carries an auspicious raider, hulking titan, and an unhinged berzerker. Maya has a plague fox, bullet witch, breakneck banshee and a cunning binder. Each of these get plenty of use.