Why you're not able to take certain actions faster than every 1 or 4 hours in Facebook and Snapchat
If you're running rules that duplicate, change bid or change budget, you'll notice you're given the option to control how frequently the action is carried out.
This is how often you want the rule to take action on the same ad set/squad, if it still fits the rule criteria the next time it runs.
Whilst your rules will run every 15 or 30 minutes (depending on your plan), rules cannot duplicate or change budget for the same ad set/squad more than once every 4 hours, or once every 1 hour for manual bid changes.
This is how often Facebook and Snapchat's APIs will allow these changes to an ad set.
This is why the minimum time frame you can select for a repeated change to an ad set (duplicate, change budget, change bid) is either 4 hours or 1 hour.
You can find out more about this in our article here.