Engagement program vs nested Email programs for the same nurture, and how acquisition reporting behaves when a lead changes streams

Hi all,

I'm designing a nurture that has to serve three audiences from the same set of emails, and I've hit a fork I keep arguing myself around. Posting here because I'd rather hear how people who run these builds actually decide.

The scenario

A 12-touch nurture across three audiences (new leads, mid-funnel, current customers), same emails each time, but different timing and cadence per audience. My instinct is one Engagement program with three streams. A colleague's instinct is three Email programs nested under a parent, each with its own smart campaign and cadence handled by wait steps. Both are defensible on paper and I can't find a clean tiebreaker.

Where my understanding currently sits

• Engagement program: streams give you the cadence, plus pause/unpause and built-in content engagement reporting. Good when the nurture is ongoing and you want people to keep cycling.
• Nested Email programs: more manual control, better when the sequencing is fixed and finite, or when each step needs its own success criteria or channel reporting.
• Engagement programs sit in their own channel, which affects how they show up in program and Revenue Cycle reporting. This is the part I'm least confident about.

What I'm actually unsure of

1. Is there a rule of thumb for "ongoing nurture" vs "fixed sequence", or does reporting needs decide it in practice?
2. How is the acquisition program set for an Engagement program, and what happens to that attribution when someone transitions between streams or gets exhausted? I can't find a clean answer on whether the original acquisition program sticks or whether the transition date matters.
3. When a lead moves streams, does program membership and status need separate handling, or does the platform manage that?
4. Is there a hybrid you'd actually use here, and what would make you switch designs mid-life if the nurture scope changed?

A sample item I'm using to test myself

A marketing manager wants a quarterly nurture for unengaged leads that restarts automatically each quarter, with reporting on which emails drove the most engagement. Which structure best fits?

A. An Email program nested under a quarterly parent program, with a smart campaign and wait steps
B. An Engagement program with a single stream, cadence set in days, and emails added to the stream
C. A default program with a smart campaign triggered by a "Lead is Created" filter
D. An Event program with a roadshow channel

I keep landing on B, but I can argue myself into A depending on how "quarterly" is read. If anyone wants to tell me where that reasoning breaks, I'd appreciate it.

For context, I'm studying for AD0-E555 at the same time, which is why I'm trying to get the reasoning rather than just the answer. If it changes how you'd respond, say so and I'll take it to the certification group instead.

What I've been using

• Experience League documentation for Marketo Engage (programs, engagement programs, acquisition, channel and program reporting). Slow reading, but the only place I've found the acquisition behaviour explained without hand-waving.
• The official exam guide and readiness questionnaire linked from the AD0-E555 page on Adobe's certification site, which I've been using as a checklist of what I should know.
• Adobe's exam prep course on Experience League.
• For timed practice I've been using the CertsPrime practice sets alongside Adobe's own materials, mainly to get used to question wording under a clock.

Thanks in advance. I'll come back and post what I ended up building once I've tested it.