ALL the music, according to the engineer, was from masters, and none from vinyl. It was clean enough that I believed him, but now,
I think maybe that might not have been true. It certainly was a different presentation.
I know that the Drake-Chenault formats were all using vinyl as originals for songs. And I HIGHLY suspect that TM Stereo Rock was as well. D-C did not use singles though, and I would also suspect that neither did TM. There are some hints if you had listened REALLY carefully.
Hall and Oates songs from Private Eyes, "I Can't Go For That (No Can Do)" and "Your Imagination" were like the single remixes, however those were adapted from 12" extended remixes. TM could have just spliced those to single length. Denice Williams' "Let's Hear it For the Boy" was edited from a 12" remix version to sound much like the single (though here I'm surprised they didn't just use the LP - it was more common, but the 12" had an edge to it). Rod Stewart's "Passion", Blondie's "Rapture", and Prince's "Little Red Corvette" were all custom LP edits, and they did not use the 45 edits for these.
There is one other possible hint. When I was working in radio still, we had TM's GoldDisc service. Did you ever notice that many of the supposed "single edits" were actually LP edits cut to length? Steve Winwood's "Finer Things", and "While You See a Chance" stick out in my mind, as does Simply Red's "Holding Back the Years". Also, a hint for the use of vinyl; on George Benson's "Give Me the Night", there is some slight surface noise at the end of the fade, and you can hear that a noise gate was used, because of the severe high-frequency roll-off at the end of the fade.
I would assume that the avoidance of using 45s was because of the higher VU level, end-of-side distortion, and other anomolies that arise from tracking records at the most inner dimensions of the disc. Whereas LPs are more flexible, so the wear is less, as is the noise. Some, or should I say many LPs can sound astonishing on even modest tables.
(sorry to babble)