Apologies if this has been covered somewhere:

Suppose you've got a two-segment itinerary.

Segment 1 is short, and R space is open
Segment 2 is long, and R space is 0

If you apply the RPU today, then it gets consumed and applied to the short segment 1, then theoretically maybe waitlisted for the long segment 2.

If segment 2 does not clear, then you've burned an RPU for a short flight.

What's the "best practice" strategy for this situation?

What I've done is to create an EF alert on the long flight, and then apply the RPU if R space opens on the long flight. Downside is the R space might be consumed by others on the WL if the WL actually clears.

If I applied the RPU now, it would go to the short flight, not the long flight, and then if the long flight doesn't clear, I've burned an RPU on a flight that was < 1 hour long.

Other thoughts?