yeah
so for reiksguard you can have one unit of 20, two units of 10, or no units
the 20 helblitzen is the minimum number you must have to be 'legal'
to be honest, back when we played 3rd edition, no-one in our group even dreamed of enforcing the required units
then again, I played a generic chaos army until Slaves was released, which didn't have any minimum troop types requirements iirc
So I wasn't about to get pissy with a mate cause he didn't have his minimum number of scythe armed skellies
We tended to take the overall points split (rank and file vs chars etc) a little more seriously though.