Something I keep seeing done in games is the idea that every AD carry should, immediately, before any other items, build as many critical chance items as they can. Phantom Dancer, Statikk Shiv, etc. Immediately. No attack damage items at all.
This...isn't a good idea. 100% crit chance with no bonus attack damage basically just grants attack damage equal to 100% of the user's base attack damage, with one catch: This bonus attack damage doesn't effect skills. This means Quinn's Harrier, Draven's Spinning Axes, Ashe's Volley, etc. all become somewhat useless, and especially during the build process, the inconsistant damage means players actually building AD and Lifesteal are not only going to out-damage them in laning skirmishes, but outsustain them after said skirmishes. And lategame, when you have two Phantom Dancers, a Statikk Shiv, and Berzerker's Greaves, how much damage are you going to contribute to a teamfight?
Answer? Not a lot. Not a lot at all. What people don't seem to get is that crit chance, much like attack speed, is a multiplier. It multiplies the damage a character will already deal. For example, 2 multiplied by 2 equals 4, but 1 multiplied by 3 equals 3. 2 plus 2 and 1 plus 3 equal one another, and that's the cost, but when multiplied you end up with less.
To this end, I must request that people do this: If you're going to go straight crit chance, your first item needs to be an Infinity Edge. It is the only item that will grant you the damage output you need to sustain such a plan. Rushing crit chance can work on some champions, but not all of them. Know your champion, know their strenghts, and don't rush crits if you can't capitalize on them.
On a parallel note, I must say this: Not every AD carry is built the same. Not every game requires the same build. If you're just automatically slapping items onto your champion because they're "AD carry items" or "that's what I saw this pro do one time," and you lose? You're an idiot. Pros alter their builds as both the game and the champion requires. Mindlessly following what they do is not how you improve your skills. Learny WHY they do what they do is how you improve your skills.