The rule says that at least one unit in the wave must have a LOS to an ennemy unit at 8 hexes maxi.
This ennemy unit must not necessary be known. It must be at 8 hexes, not 8MF, so you don't need to reach it inyour MPh.
So you can launch a HW against a dummy stack to benefit of the "speed bump", as you say, then cross 8 MF without being CX. You can even do it with unit already CX.
So the human wave can be a very good tactic when you must cross a lot of terrain in a few time:
Move CX with at least 6 MMC (one at a time), near a zone where they could after the APh have a LOS to a "weak" ennemy unit (a probably dummy stack, a HS, a broken unit, a NT tank with no MG - such as some TD), regroup them in APh to be in position to launch a HW. If they survive to the next PFph, they will return fire as a big FG during DFPh and then move of 8MF + APh in the next turn.
And because many players think that HW is a stupid tactic, you have a great chance to surprise your opponent.
Furthermore, the human wave allows you (as a berserk) to finish your MF in the location of the ennemy, so it can be a good think to freeze potential PF launchers, in order to move your tanks.
Instead of making VBM freeze to allow infantry to progress, you can do infantry freeze to allow your AFV to progress.