The orchestration limit of 600 - is this the total no. of orchestrations defined or no. of instances of orchestrations running?

@Ash Aragam that would be true yes. I've been speaking on Orchestrator for over a year now within the Trailblazer Community. One of my key points on this subject is to encourage Flow Builders to use Entry Conditions to prevent Orchestrations from unnecessary runs. I use the scenario of 10 people refreshing a page with an Orchestration that doesn't have entry conditions attached to it 6 times in a day, and then going on to follow that pattern for 10 consecutive days ... if you do that you'll use up all of your Orchestration runs within 10 days. It's a bit of an extreme example, but it covers how Orchestration runs works and the ease in which orgs could eat them all up very quickly.