When creating a network flow formulation you can set up sinks with integer flow requirement $\ge 1$. This yields solutions with the total amount of flow along an edge.
I have also seen this as a real positive number between $0$ and $1$, the latter inclusive (i.e. $(0,1]$). Derived by dividing the sink demand by the total demand.
What are the benefits of the approaches or are they considered equivalent?