DISCLAIMER/CAVEAT: This modelling practice/policy has not been applied on every older Diagram slide page on this site, and also not on educational materials just introducing Dependency.
Dr Darren explains:
For systems modelling with SysML, I now employ a strictly "reverse time ordering" policy with basic Dependency, as a default, no exceptions. If I then want to use it otherwise, I custom stereotype it (to give it another rule/policy or semantics).
The Dependency MUST according to this policy (which goes beyond SysML and UML) go from something that exists later in time to something that existed before it in time. No exceptions. This enables you to trace nicely from Sinks back to Sources time-ordered. It helps reinforce the signal processing idiom I insist is your best friend when SysML modelling (but at a higher level of abstraction without the port-based engineering).
I then reserve Usage (the actual meaning of which is notoriously vague) for Software style dependencies, sometimes with custom stereotypes, as well as Package Imports or Element Imports.
By rights I "should" be introducing an additional custom Stereotype extension and keyword for Dependency to indicate where this policy has been applied, but I am now using this policy so often that I am lazily (conveniently) using it as a default policy whenever using Dependency in systems engineering Diagrams, and only applying a custom stereotype whenever the policy is NOT used.