@lindav - I usually set things to “Manual” while I’m reviewing or testing the various Flow Trigger or Filter Logic, and various conditional branches in the Flow.  When I’m confident that it’s working, buy looking at the emails that it would have sent (had it been Live), I then switch it on Live so that the process is automated.  From my experience, 99% of the time, the goal is to get a Flow to be Live and automated so that it can send emails as timely as possible, and also not require someone to manually do the work.  This is especially true if you have hundreds or even thousands of emails in dozens of different Flows!

Though there are some times where “Manual” might be helpful outside of the building/testing/reviewing process.  For example, for one specific client, we have a Flow that sends an email if Shipping is extremely delayed (a calculated time between Purchased and Fulfilled past their standard shipping/processing time) and we set that message on Manual.  When the operation team has confirmed that Shipment will indeed be delayed due to unforeseen issues, they go through the Manual queue and manually send the emails to those who may have been impacted.   Otherwise, they just cancel/clear the queue if Shipment is still within the range of accepted time according to their shipping policies.

@retention thank you, this is super helpful! It seems like my flow qualifies a good amount of past customers so I am working on my email content and then set it Live.