I've seen various solutions/workarounds but this seems to be a table-stakes ask?  When scheduling a workflow I should be able to specify which parameter values to run with.  Just two of many use case examples - 
Use case #1 - a single analytic app could be scheduled multiple times, each schedule specifying a different line of business
Use case #2 - credentials, allow the user to schedule a workflow with their saved credentials.  When their credentials change all they would have to do is update the schedule parameters
 
(If you know a better way I'm all ears, not the API thought that isn't a bad way to do it, just not super Easy)
