I've found that I have a number of habits that have carried over from old skool Wow. Most of these have changed as the game has evolved (such as using my own epic flyer to fly some place instead of wasting the gold to use the taxi service), but some of them have carried over (such as continuing to use IF for the AH and visiting the same auctioneer every time).
But I found that one of my habits has to do with how I perform in the game. And this one is a bad thing. You see, I still remember the days when there were super powerful spells... spells that were so strong that they were almost like instant "I Win" buttons. These spells were so powerful that they got put on these ridiculously long cooldowns. Spells for example, that would blast a target with a pyro so large... that it would continue to burn long after impact, or a spell that would put up a shield that was as big as a wall, or a spell that would allow your to spiritually lay your hands on yourself or another player to instantly heal them for an insane amount of health. These spells would have cooldowns of days... or at least what seemed like days sometimes. But as we've progressed through the various versions of Wow, they've slowly lessened or removed cooldowns for these special spells.
But I still treat them as special. I still have something in the back of my mind that tells me that I should save them for special occasions. Certainly I'd use them for a boss fight, but trash? Unheard of!
And this habit carries over to new spells as well. Take Mirror Image for example. It's only a 3-minute cooldown, so I should probably use it pretty much every chance I get. Heck, if we're doing new bosses it guaranteed that the explanation alone will take more than 3 minutes. Furthermore, even on the boss fight, I'm afraid to use it until the right time. I want to wait for heroism.. I want it to be at the best time... Heck! If we're using heroism at the end of the fight, I probably can pop my clones towards the beginning of the fight and be able to cast them again once heroism starts.
Granted, I haven't been playing my mage much, so it's not like I recognized it from my lack of not playing my mage. No, this time I was looking at spell rotations for my wife's shadow priest. And for all things shadow, where do you turn? That's right, ShadowPriest.com. So, in the standard rotation, they start off with spells to start buffs and debuffs, get a little damage in, and then BAM! Shadowfiend. But... but... you're supposed to use that only when you're almost out of mana, right? Granted with a normal Shadow Priest, it's on a 3-minute cooldown, not 5. But it's not just about mana, it's also about increased damage. And it's not like it's a 30-minute cooldown, it's only 3.
So, while I'm sure that I'm the only that still has this "issue" remember to use your cooldowns on a consistent basis, not just when the raid leader yells, "pop all cooldowns!"