If you're not playing ADC, anything less than 20% CDR (@ 6 items) isn't enough.

For example, on something like Jax or Irelia my philosophy is if you want , go for it but also get for it's CDR and Mana.

There's no way, regardless of whatever steroids the champion has on AAs, that you can say that Auto-Attacking is more valuable than sticking potential through use of Dashes/Blinks and CC.

So many times I look at a champion in the late game who is just getting kited and becoming rather irrelevant, then see their build with only ~10% CDR and I just say "well that's why".

So much of a champion's effectiveness is tied up in their Abilities, yet so many people forgo building CDR. I get ABUSED for building on just because you lose out on 400g worth of stats. They don't even acknowledge how cost efficient the item is anyway. 2450g for 100 Armor, 20% CDR and an invaluable Aura is more than satisfyingly cost efficient. Not to mention I get RIGHT AFTER because the Aura from FH and the Passive stack so well.