Originally Posted by
sbm12
At one point UA stopped allowing the single instrument to apply over long (an arbitrary definition) layovers. That rule seems to come and go and is always unpublished when it is in place so who knows if that's a thing right now or not.
The website generally follows the same rules as checked baggage and where it draws the little banners in your reservation display (something like 13h and/or overnight), but an agent can do anything. This year the best I've done is NRT-GUM (10h overnight)-HNL (18h overnight)-LAX-SFO, on a fare component which included [GMP-HND(24h00 overnight)] to start on OZ, which of course wasn't eligible.