I applaud your versatility. (No sarcasm intended.) My point is, this thread is about the basics of effectively using Destruction Magic. Your advice is "Enchant 4 pieces of gear with 25% Fortify Destruction, and don't invest in Magicka." That's great, but that's Enchanting, not Destruction. If you're going for pure Damage, then you probably already know that you can do more of it with a Bow than with Fireballs. (Even riding a Dragon.) What your advice boils down to then is don't learn to play a Mage, break the game so you don't have to. Dual Casting forces you to use targeted Spells, because they don't work on others, like Wall of Flames. What I'm saying is, if you learn All spells, in All elements, you can get better performance than just dumbing it down to "Impact, 'nuff said." (Not quoting you, but I've read that exact thing several times from different people in countless places on the 'web.)
With that strategy, the most powerful spell you have at your disposal is Incinerate, with Augment Flames, and Dual Casting, that's (75x1.5x2.20) 247.5 per casting+On Fire damage. Of that, less than 10% is from Dual Casting. For contrast, Wall Spells do 75 damage per second for 20 seconds, per incidence. With a Grounded Dragon, for example, you can hose down it's entire footprint with 2 different elements to stack up countless incidences, and finish it off in a few seconds. (The effect lasts longer than the Dragon does, even with Ancients, or even Alduin, I tested this on Master in a Loincloth.) If one of those Elements is Frost, even if it's Frost Resistant, then it can't take off, and you only have to use Dragonrend once. I know, you have Bend Will, so you can just hop on, and ride off like a boss, and this tactic doesn't work mounted, but that's not every fight, and it's useless underground, or in close quarters where you can't even summon Odaviing.
These are just examples, to illustrate my central point. There is a wide variety of spells, and effects just within Destruction. Now, you can use, or teach people to use 1, or 2 effects, or you can learn to use all of them, or as many nasty combos as you can come up with, and share them with the rest of the class. The Stat most associated with Mages in every game I've played with Stats, and Magic (Including earlier versions of TES) is Intelligence. Most of them add that it's what gives you Magicka, or Mana, or governs how many spells you can learn/memorise/cast, but the real idea is that any idiot can play the Damage Race with Weapons. Harnassing, and directing the elemental energies of the universe effectively requires reason, and intellect, not just to figure out how these forces work, but also what to use when, and how. It's complicated, so you have to think.
I feel much the same about Free Destruction. Mages use Magicka, that's why they put it in the game, added all those items, and perks to reduce, and regenerate it. Enchanting so it's no longer an issue isn't playing a mage, it's making your character into a Staff of Fireballs.