On my non-structured interval days, I often just do long endurance rides with a pace partner on Zwift. These end up being pretty consistent wattage, without a ton of variability.
After the ride - is there any value to TR’s algorithm if I find a similar specific workout in the library and pair them - or fine just to leave it as unstructured?
No, there is no value in doing that. Just leave them as unstructured workouts.
I personally do do this, but only if it’s a structured outdoor / structured zwift ride - e.g. it meets the workout goals and intentions and I have that workout in mind going into the ride.
Here’s an example - 3 hour Z2 ride at 200W. I create that custom workout in TrainingPeaks, it loads to TR as a custom workout. Ride with a Zwift Pace Partner. NP and AP almost equal, right around 200W. Match the rides after. I’ve also done this for interval workouts outside when I’m riding a flat TT Loop or rail trail I have here and I’m executing the workout as prescribed. Basically - not a lot different in this case than if you’re riding the workout on a trainer in resistance mode.
I do NOT go looking for a ride to match to after the fact though, basically “why” I do it is so it’s easier to see at a glance if I really executed the workout or did something else.
I thought that was what Solo Rides and Group Rides were for, associating an unstructured ride with a TR workout. If there’s no point, why have those options?
I’m hoping the ‘new and improved’ imminent update will simply take all activities, structured and unstructured, into account in adjusting the plan.
not to a specific workout but reading the article it indicates it will give you some general intensity guidelines for that ride.
Right click on a workout in a plan and it can be converted to a Solo or Group ride. IDK, but I took that to be an “association.” What I did, right or wrong, would change the workout to something with and IF and TSS more like my outdoor ride, and then turn it into a Solo ride. My presumption was that doing the outdoor ride would then be taken by TR as having completing that workout. Why else have that functionality?
Yes. Def hope that’s going away and the New and Improved TR will take all into account in adapting the plan.
Hey @GravelSteve 
Many good answers already !
If you are not following the TR Workout instructions, then we don’t recommend matching them, even if the effort is “similar” they are still two different things.
In your case, since you’re riding in Zwift, I would just let the ride file sync to TR and the system will adjust the training plan if needed!
As far as Solo/Group Rides go, these can be helpful to add when they are recurring and part of your training schedule as the workout cards will have instructions on how to tackle them so that you exercise the energy systems intended for that day.
For example, swapping an Endurance TR Workout for a Solo/Group Ride when riding unstructured outside.
More info here: How to Add Group and Solo Rides to your Training Plan
Note: if these are manually added Solo/Group Rides the workout cards won’t have descriptions as they are not part of your training plan schedule.
Super helpful - thanks @Caro.Gomez-Villafane !
Welcome @GravelSteve !!