Here's a short explanation of the 'Limits' section in your Phantom's Step 2 advanced settings.
'Limits' exist to let you restrict how much your Phantom can do. This is useful to you if you want to save your execution time or monitor how much is being used up.
Here are your options:
Execution time limit (minutes):
The maximum number of minutes your Phantom can run per launch. The maximum possible execution time limit is 300 minutes (but may be lower depending on your plan).
Maximum parallel executions:
The maximum amount of launches your Phantom can run simultaneously (for example, by having a launch scheduled to start before the previous has finished). If you choose zero, this will mean unlimited parallel executions.
You want to avoid concurrent launches especially for Phantoms who send messages or post comments.
Number of retries:
The maximum number of times your Phantom can reattempt to launch after having encountered an error (this may be an error in launching or an error while running).