Those extensions really bothered me too, considering she has a feathered look in X2, similar to Storm's haircut now. What Phoenix had - had to be at least two years worth of growth.
		
		
	 
Have you ever grown your hair long? I have had my hair down to my butt, and it certainly didn't take me two years to do it. Currently, I've gone from close-cut (not buzzed, but short) to shoulder-length in about 2 months.
Two years? No. Maybe a year, for some people, but it varies from person to person.
It also helps to be able to MAKE A HUGE EVOLUTIONARY LEAP, like Phoenix did.
So let me get this straight:
1. Jean Grey holding back a flood?  Totally believable.
2. Jean Grey taking over Prof. X's brain to say "good bye"?  Totally believable.
3. Jean Grey not being killed by a massive, crushing wave? Totally believable.
4. Jean Grey evolving into the most powerful being on Earth? Totally believable.
5. Jean Grey being able to incinerate people with a stray thought? Totally believable.
6. Jean Grey growing 8" of hair?  OMG!!! IMPOSSIBLE!!!
I bet you're the guys who are looking for the wires in Superman, too.