How do training suggestions work? Are they adaptive in any way?

Both training suggestions and training plan are fairly well balanced for me, maybe even a tad lighter than what I could pull off. I've set it up for the upcoming marathon and while I'm not using the watch's plan, I keep an eye on it for the sake of comparison. It jives well with the plan I'm actually using in terms of overall load, quality runs, and long run.

And the workouts are definitely adaptive. The watch is keeping track of your load, recovery time, and load balance and adjusts the schedule and runs accordingly. In fact I wouldn't be surprised if they started tracking HRV status we well -- I got a rest day today all of a sudden, and the only thing that stands out is a depressed HRV trend.

Are you on 9.33? Please check your training load/history, lactate threshold and heart rate settings. How do the derived physio values like predicted race finish time and VO2 Max look like? Are they realistic?

I've just updated to 9.33 and have not run with it yet. Garmin completely overstates my VO2Max by about 10, always did. So that's a totally useless metric. It also massively overstates my 2 months ago tested LTh. I have custom HR settings, and they are fairly realistic. maxHR is ok, when after a run Garmin calls something a threshold run then it's actually one. Yet when I set the training programme to HR based it gives me a HR for a threshold run much higher than that, more close to a max effort run. And when I chose pace as metric then even the slow runs are much faster than I usually run, and certainly much faster than my slow runs. So it's all a bit messed up. But it might be me because my actual data is messed in that I have a muscle condition that a) makes running not quite so easy and b) results in somewhat unusual metrics. Just checking whether this is adaptive and might go down at a certain time.

I don't know... for me it looks like Garmin ignores my own custom data, puts too much emphasis on VO2max and puts some too high pace or target HR on top.

My suggested workouts work pretty well. Close in pace and duration to what i would train to even if not following a plan. I find it also works better if you use the race widget and have a race coming up so the suggestions are tailored to that race. 

Today Garmin is giving me a threshold run. Which is indeed what I aimed to do. Only funny that the suggested pace is more than 2min/km faster than my usual threshold runs. And faster than any run in the past 3 years, from before I even had a Garmin. This is rubbish!
I don't do races because my pace is too slow and I might get carried away and run faster than usual - and end up in hospital. Not good.