Acceleration and Max Speed Volume and Breaking up Total Volume

If both are done at max velocity, the flying 30s must be harder on the CNS ( you have to get up to the starting pace going in, move at a higher rate throughout, and be at your max possible speed by the end of the segment.)
5 x 40 is easier than 10 x 20 blocks. Not sure how to think of 20 x 10. If that took the form of med ball accel drills or some such (as it most likely would), it would be easier on the CNS than either of the others.