Check coverage limit reached?

I have a bunch of iPads for which I need to check the warranty status. After about 5 serial number I input, I receive this message:

Check Coverage

We’re Sorry

You’ve reached the code limit and we’re unable to complete your request. Please try again later.

Please return to Apple Support site.

To me, it looks like Apple is not letting people spam their warranty/coverage check tool by limiting the requests a user can submit...

This is pretty problematic for me because if I can only input 5 iPads S/N at a time and that I have to wait a long time (60 minutes? maybe more?) before continuing on with the rest of my bunch, this is gonna take a looooong time to finish...

I work in a schoolboard and need to do the inventory of the iPads we have, and their warranty status.

Any idea if there is a way to check the coverage status of many iPads without being blocked from doing so every 5 serial numbers?

Thanks for your input!

- Alex