adding a smart campaign into engagement program

One thing I could not find an answer for anywhere is. When you are using a smart campaign as "content" in a engagement program, what do you set the smart campaign's schedule to?

For example, the smart campaign i'm planning on using has these attributes:

smart list: member of program xyz, in stream 1

flow: send email, random 50% send email 1, else email 2

Schedule: ?? this is where I'm confused. do I need to set a schedule here to match the schedule set on the engagement cadence? How do I ensure that as I add new leads into the engagement program, they are still receiving emails from this smart campaign?