Question about attack speed

As non-career ARC myself, I am a little confused about working out a Bow's DPS.

In a recent dev note, they mentioned that Ul'dah's GC bow isn't as obviously better than the other GCs' bows due to the slower attack speed.

I was under the impression that light shot recast was a set time. Is this not so?

Bows have different delays, but from my understanding the action bar/action list will always say it has a 4 second recast, while in practice your delay will be shorter/longer depending on the bow.