This setup is far from ideal. Why would you define your Engaged Audience as those who engaged during the past 30 days? It should be the widest net possible. All Website Visitors during the past 180 days. There’s no reason to eliminate some of the engaged people based on page or those beyond 30 days. Then the overlap is easy. If they bought something during the past 180 days, they are an Existing Customer.

Audience Segment is defined as follows
Engaged
– All Visitor, Product Viewers, Add to Cart | 30d
Existing
– All purchaser 180d
– All Purchaser customer list lifetime

Now anyone who is visiting and purchasing for the first time will end up doing the engaged tasks and existing task, what is the cutoff or how frequently does it checks the audience segment.

TIA

100%. Im normally running a prospecting and a retargeting campaign as a standard setup, but i am now testing just having 1 campaign completely broad with no exclusions or anything and i turned off my RT campaign as well. So far the algorithm is around 30% of the budget on "existing customers" and the rest on new audiences. Its does kinda seem like having a dedicated RT campaign is kinda redundant these days as the algorithm will do retargeting on its own anyways it seems like

I hear you. We all make judgments on what is trustworthy. I have Meta developers reach out to me often. This was not a random thing. And it’s 100% reasonable that it would work this way. It makes less sense that you’d need to exclude since that’s virtually impossible to do.

If you want to attempt to exclude people in every custom audience to guarantee there’s no overlap, have at it. But it doesn’t appear to be necessary.

Alright. hmm , Im not saying it cant be true what that guy said to you… but some random person reaching out to you and claiming stuff like that is not 100% trust worthy source in my opinion

I linked to it in that passage. Someone from within Meta reached out to me to let me know.

https://www.jonloomer.com/qvt/do-you-need-to-exclude-existing-customers/

ahh i must have skipped that when i read. Do you have a source for that statement, did Meta come out and say that?

I covered that when discussing the Engaged Audience above. “There will be overlap — not only between custom audiences within Engaged Audience, but between your Engaged Audience and Existing Customers. Do not worry about excluding people to prevent that overlap. People will only be counted once. If someone is shown your ad who exists in both the Engaged Audience and Existing Customers, they will only be counted as an Existing Customer.”