It's of course based on what's more important for you: Running tests non-stop and perfectly utilizing a compute instance vs having the tests executed when you need the results as soon as possible. I might argue that in most cases the latter is what you'd actually want. Especially given that you're getting billed on a millisecond basis.
I would love to have something like this for my scala API tests. We have 3k tests running on 10 ec2 instances and the entire test-suite takes 10 minutes. If some infrastructure would allow me to pay a little more and run all tests in parallel, that would be a game changer for our team.
