Have been doing this for nearly 3 weeks i believe.
started at L3 and it initially kicked my behind and gave me a good ahce.
progressed last week to Saturday - L3D1 22 sets
Monday - L3D2 4.57 min
Wednesday - L4D3 4.35 min
2 days ago I did L4d1 28 sets in 20 mins and no ache at all, appart from minor in the quads.
Seems I am adapting quickly as you do for any new exercises, will be interested to see when I get my increase at a decreasing rate.