When scheduling talks in a conference session, what is the etiquette, if any, regarding placement of multiple talks from the same research group? I am the lead co-organizer of a symposium at a technical conference later this year.  The abstract submissions are now closed, and I'm working on slotting the talks into sessions.  With the number of abstracts we have in hand, I'm planning to spread them across three sequential sessions in a single chronological track. In the event it matters, the symposium scope is intentionally very broad, so the speakers in any given session may (justifiably) have little interest in attending the other sessions before/after the one in which they're scheduled.

There are a handful of research groups that have each submitted two abstracts to the symposium, with different presenting authors. All of the abstracts are in-scope and distinct from one another, so I plan to accept them all. 

What is the etiquette regarding scheduling of such talks, submitted by the same research group but with different presenting authors?

Should I specifically aim to schedule them close to one another in the agenda? Should I intentionally interpose talks from other groups? Or, does it not really matter?

From the perspective of the presenting research group, it would seem most convenient logistically for the talks to be grouped together in sequence. That way, the whole group would have the option of attending just the relevant small chunk of the session, with the rest of the morning/afternoon more free to attend other talks.

From the perspective of a symposium organizer, though, it would make more sense to separate the pairs of talks, in an effort to make it more convenient for the speakers to just stay in our session track, rather than bouncing back and forth between our session and others.

It's also entirely possible I'm just overthinking the matter.
You have to plan the symposium from the audience’s perspective, not the individual research group’s.

Presenting multiple talks from the same group back-to-back or even within the same session can become tedious, even if the work is nominally “distinct.” If I were planning multiple sessions, I would avoid putting abstracts from the same group in the same session, but instead spread the pairs out evenly among the three sessions (if possible).

If your sessions are thematic, I’d still try to separate the talks within the session, so that the talks are not back-to-back, but perhaps “bookending” the session or nearly so.