Hey @SteveH
The segments you set up according to the article you shared in your original post will automatically choose who should be in which engagement track, i.e. all your customers who have high click and open rates will be in your most engaged segment and are the group that you can send content to everyday if you wanted to without potentially negatively impacting your deliverability.
How often these different groups get emailed will still be up to you. But keep in mind you don't want to email your less engaged customers frequently, so their flow may only include a few emails that are separated with a time delay of at least 1 week. Knowing your customers will be the key to how you setup the actual flow, and how often you are sending them content.