Schedule a site workflow to run every few minutes

What is the actual requirement?  Could you use a loop instead?

The workflow is basically retrieving entries from a Wufoo form and the form is expected to be used quite often.

This is why I would like it to run for shorter iterations.

Can you please explain how I loop the workflow?

Thank you!

can you show me the site workflow you have created so far please?

and confirm if you have safe looping enabled on your farm (your farm admins should be able to tell you this)

Have a look at Vadims script here