CK3510 coming off regen

Well least it was at end of day and almost out of fuel so I quit. This was the 2nd regen, and it would've been nice if dealer or manual said that the BRAKE has to locked on for the regen button to work, after pushing button 15 times I tried with brake on and off it goes. So 20 freeken minutes on 3000rpms then anther 5 minutes on 1500 rpms, how can that be good for an engine. I wonder if I should've bought a Mahindra I dont trust this regen, but then on other hand this tractor is getting around 30 hrs on 7-ish gal full tank which dont make sense, my Kubota L340 gets 7-9 hrs on same size full tank......