Last year for my birthday, I redid L1 and the following day L2. I then turned around 2 weeks later and did L3, followed by L4. This year, again for my birthday on the same track I did L4 again. I rode the BMW S1000RR and had a blast!
I didn't take lap times, but I could easily perceive my pace was quicker, smoother and safer since the last time I was at the circuit. I took a couple wins with me in that I realized at the consulting table with my peers that I went through the day and not once had a pucker moment. I had control over myself and the bike, even during the time when I blew my TP for T7. My other win was that I completed the day without the nagging of back pain that has come up over the years.
I was able to use many of the L3 skills that I picked up and I also realized some areas where I can expand my new capabilities into and remove some old limitations.
I can also say that I've had the pleasure of winding the S1000RR to WOT on the front and back straights. Maybe in the soon future, I'll be able to hold it there!