There are a variety of ways to run an email campaign.
You could send out a new email to everyone each day/week/month. This can work great for timely information and is the easiest campaign to start and maintain.
You can also setup a specific sequence that goes to everyone based on their individual schedule. So everyone gets Email #1, then Email #2 3 days later, and finally Email #3 7 days later. Everyone would end up getting the emails in order but on any given day, you'd have a mix of emails going out.
The second one, the sequence-based one, takes more planning and effort but you can do more with the campaign because you know they've already seen the previous emails.
I use a mix of both.
My Daily Shopify Tips are the first type, everyone gets the same tip when I publish it.
Customers who signup for Repeat Customer Insights get a second campaign, called the App Onboarding. That campaign is a collection of emails describing how to use the app and what to do with the analyses.
I recommend Shopify stores have a similar setup with at least two campaigns.
New customers would get a set sequence of a New Customer Welcome campaign. It could cover how to use your products, customer service questions, community, and anything else you'd want every new customer aware of.
Every customer, no matter how long ago they purchased, would get your regular newsletter that you send every month/week/day. This will have content, education, jokes, sales, etc.
More advanced stores might have a non-customer campaign also that's similar to your newsletter but kept separate. Keeping them separate is harder to manage but it would allow you to send more specific offers to customers vs non-customers. I don't bother with that.
Just be careful of complexity with email marketing. Adding too much code, logic, or marketing automation to email systems usually results in mistakes and bugs. I've seen all manner of bugs come up with a number of vendors and they all result in unhappy subscribers.
There's nothing wrong with simple.
If you don't have a New Customer Welcome campaign and regular newsletter yet, now is a good time to get them going. Year-after-year email ranks as the top converting sales channel across Shopify stores and there's still enough time to get it setup and ready before Black Friday.
Optimize your promotion timing to save money and attention
Repeat Customer Insights will analyze a ton of customer behavior data for you, including their buying cycles.
If you knew exactly when the majority of your customers were ready to buy again, you can increase your orders and profit just by tweaking your message timing.