Creating a list based on number of emails opened

But wouldn’t “sends since last engagement” be 0 for newly enrolled contacts?

How would I know if the person has even received 10 emails since?

For example, this property would be 0 for a person who has been opening my emails continuously, and they could’ve received 25 emails from me overall.

But it would be 0 for someone who fills out a form and enters the CRM, too. Unless my understanding of how this property is wrong.