this actually sounds interesting. do you precreate the workers beforehand and then just keep them in a stopped state?

yeah. one of the goals was startup time, so It made sense to precreate them. In practice we never ran out of free machines (and if we did, I have a cdk script to make more), and inifnite scaling is a pain in the butt anyways due to having to manage subnets etc.

Cost-wise we're only paying for the EBS volumes for the stopped instances which are like 4GB each, so they cost practically nothing, we spend less than a dollar per month for the whole bunch.