well I only started stretching again like a week ago, before I stretched regularly cause I did musical theatre, but cause of corona, it stopped and I stopped stretching. But that means my body was already pretty flexible. I think my body is more flexible now, esp my left leg cause I know that leg is less flexible than my right one and now I stretch my left one more. It took me about 3 days to notice.
I starter stretching before trying this app but I think it definitely made a difference in matter of days. At first you might feel soar, I did due to stretching pretty intensely, but as soon as the soarness is gone, I felt much more flexible. However I am very young so it is probably easier for me but putting in the effort to become more flexible is in my opinion worth it. It is fun to see improvement and also really good for you long term health.
At first I felt some pain and felt quite sick and exhausted. I am slowly becoming more flexible. I notice I can stretch further