At the start of the Duke tour they were opening the shows with NYC. The 'heartbeat' lead-in for that remained when they made Motherlode the opener. NYC moved further down the setlist then got dropped but briefly reappeared near the end of the tour.
After this it became rare for them to resurrect unexpected older songs, which was a shame. It would've been a nice setlist policy to include one entire old song per tour. It would make a faithful section of the audience happy while not compromising the band's approach of focusing mainly on the last 2 or 3 albums. The Abacab tour resurrected FoF in its full length rendition for the final time (I think). In 82 they did all of SR and the Watcher edit. The Mama tour saw the one-off medley of bits & pieces and the Quiet Earth fragment, then in 86/87 we got the whole of it and on some dates the end of SR.
By the WCD tour they'd really minimised the old stuff, even the stalwart of Los Endos was gone, leaving just the medley of bits. I can't think of another band that was so unsentimental with their older material! I was conflicted on this as I would have loved to hear older stuff but also respected their approach.
Re the Six Of The Best gig it's the other way around in that it drew on recently performed tracks eg NYC, Moonlit Knight/Carpet Crawlers, SR.
I saw them twice on the 1980 tour in Southampton, the first was the cancelled Bournemouth gig where the venue was slightly smaller and my mate managed to get two tickets for the back of the stalls. Both times they opened with Deep in the Motherlode.
The difference in atmosphere between the two gigs was extraordinary. The "Bournemouth" gig was subdued and most remained seated for the majority of the performance. The official Southampton gig was electric with a good old fashioned rush to the front when the lights dimmed. This probably went a long way to explaining why that show got the second encore (The Knife) which the first didn't.
They were my first and second genesis gigs respectively, but far from my last!