Interesting. I now understand that you are quite sophisticated wrt nav.

Two things come to mind. First, I would suggest that marine TBT nav is fundamentally different. Marine routes are typically made of few waypoints (20 or less) and you navigate in a straight line, often for hours, between waypoints. In my experience, once you've reached a waypoint, your GPS asks you to confirm that you want to move to the next. Hit a button and you get the new bearing displayed on your MFD (and likely sent to your autopilot as well). This process wouldn't make sense for bike/car routes, where there are many more points (because we follow twisting roads) -- you do not want to press <next> at every turn or twist of the road. So your nav app must make a determination as to where you are headed. As long as you stick to your planned route, it more or less works. But if you stray, your nav app (typically) makes no assumption as to where you should be headed -- it has to recompute a new route to your destination.

Which brings the second point. When touring, we often improvise because we want to explore/take a side trip/made a wrong turn/etc. The dilemma is that automatic routing is underwhelming. If you leave the auto-recompute on, more often than not the new route isn't what you want it to be. If auto-recompute is off, not at all clear that nav can resume once you get back to your planned route (my experience is that newer units resume TBT not long after you've returned close to the planned route, but I wouldn't bet the farm -- Google maps wasn't able to resume. It may have been fixed. Don't know for sure. Just to be clear, Google Maps TBT works offline as long as you stick to your route. If you stray, I believe that you're toast.).

I've purchased the Edge Touring a few years ago, and ditched it. When I need complex routing (eg. navigating a large city), I use a smartphone. Google Maps would do, but prefer Locus Pro/Android (fully functional offline, possible to do reasonable manual edits of your planned route, option to overly data fields, etc.). If I ride on open roads or trails where TBT is fairly obvious (time between waypoints is several minutes, and not too subtle such as five tracks fanning from a given point) I prefer to push my route to a smartwatch (F5 in my case). Battery will last for several days and there's less hypnosis (I tend to stare at my nav screen....).

So, back to your concern. I'd try (driving) a simple route with and without recalculate to determine how your Edge recovers. Ideally, do not recalculate -- if you stray, TBT will stop working; what happens once you've returned to your route? Increase the complexity and see if your previous conclusions still hold. Eventually, compare your Edge to your phone's behavior.