alt Hacker NewsHertz is fixed frequency. Say you poll x times in second with set intervals. It is not measurement of discreet events say packet arriving. Probably best just to leave hertz out unless it is something that is actually fixed rate. So just leave it unitless.
If you define frequency as the derivative of the phase with respect to time, then you also have an instantaneous frequency which (at least formally) also has Hz as unit - even though it does not necessarily describe some real periodicity.
To measure discrete events, I would prefer as unit "events per second" instead of Hz.