Standard lock is 600ms, not 635ms. A player needs <34ms to double weave without a clip on a 2s gcd before further considerations. Lower ms for < 2s gcds.

Rotations are not just the gcd when you consider the benefit of speed you have to account for the proportion of total damage and a rotation that does not care for it at all. Even if suddenly gcds were longer and scaled with speed to make it more of a usable stat, that would not alter the status quo of avoiding it on jobs that benefit much less from it in general.