There just wasn’t very much going on in Torn Curtain. It felt pretty standard, and by that time other filmmakers were doing Hitchcock better than Hitchcock with things like Charade. Marnie had the benefit of the psychological stuff, which was interesting, and most of Hitchcock’s old crew.
I’m not necessarily saying Torn Curtain is better, just didn’t seem to be a chasm in quality between them. You make a good point though. That it came out in 1966 is kind of weird, honestly. I feel like he would’ve made that same film the same exact way had it been decades earlier. Certainly fairly basic for him.