We should be able to apply load balancing logic in Workflows, e.g. set up an action allowing only x number of actions to continue every y seconds/minutes/hours/days.
This is necessary even when working with HubSpot's own API to ensure not to hit burst limits, and for less robust APIs this is even more crucial.
We've had to run 4-5 API calls on ~100.000 companies at once, and we had to build out a huge load-balancing workflow with code.