I was intrigued by the title of your post as I think it is something all of us in the MTM/Windworks program have experienced. I have to say that Hajo and Julie have some great insights and I totally agree with their input and advice.
I have been working on Windworks for about 10 months, and like you, have found it to be an up and down journey.
Suggestions Greg has made to me include more eyes closed work on the Cycle of TEE’s, including “no notes” (which I have found helpful). Something I have attempting to do lately is to budget my time on Windworks to under 60 minutes per day, so I still have time to work on other aspects of my regular playing. I have found this to limit my frustration and I feel I am not progressing any more slowly than when I was pushing hard and spending more time.
Like you, I am unable to play in V2 mode yet, but I have noticed some improved endurance and sound quality in my regular playing. I have no idea why this is happening, but I assume and hope it is from my work in this program.
I would encourage you to trust the process, as Hajo and Julie have advised, and welcome the uncomfortable feeling of learning a new skill. I used to tell my math students to welcome the discomfort because it meant they were learning. I would say to them, “there is no comfort in your learning zone and no learning in your comfort zone”. I heard this; I believe from one of my professors many years ago.