Yes, currently a skill cycle has to be completed before the next can begin. And as you mentioned, a speed of 10 will take exactly 10 seconds (1 / [10 / 4000] = 400 world cycles at 40 cycles per second = 10 seconds), so a dude with a speed 10 skill is going to be sitting around for a long while. But if we try to interrupt these cycles, I'm sure loads of bad things will happen (and then there's the question as to whether or not the cycle was completed; since an attack could appear to be completed halfway through the cycle). A cooldown period would be a useful measure, but it'd have to be something other than a skill, as a skill would just mean that the unit would have to sit there for the entire cooldown period. So just an uncorrelated timer?