Yeah, it's something that needs to be tuned per-service. It is quite easy if the service is X-bound for some local resource X (CPU, disk, flash, network card),

Yeah, it's something that needs to be tuned per-service. It is quite easy if the service is X-bound for some local resource X (CPU, disk, flash, network card), but if it is bottlenecked on external service calls it can be quite challenging to define a representative stress metric.