fly autoscale aims to scale down more quickly than it aims to scale up (1-2 min vs. 10 min)
Because of how these conditions are measured and applied, it’s a bit harder to trigger synthetically than you’d expect, and generally works more reliably for higher soft_limits (20 is the default).
Incidentially, we’re working on swapping out our scheduler; this move will help us improve autoscaling as well.