I think there’s some correlation, though it’s not 1:1. Like the Beast of Burden events that use the Erie Canal towpath between Lockport and Middleport are almost entirely dead flat on crushed gravel with potential for fast times, but I wouldn’t recommend to beginners – not enough variation underfoot or in the scenery.
Also there’s the whole timed loop race category which I’d prefer to exclude but are often both fast and good when first trying to hit ultra distances.
Green Lakes 50/100k is probably the fastest I’ve run in the region and one I would wholeheartedly recommend – beautiful course, limited vert, tons of aid accessibility and cushy surfaces.
My friends in PA tell me Blues Cruise 50k is both fast and good for beginners – several of them ran their PRs there – it also has the distinction of being one of the few courses I know of that is a single 50k loop. I’ve never made it out though.