My one putt % is 38.97%. Not the greatest in the world, but adequate. My problem is more aim rather than speed. These adjustments have worked for me:
Fast (9) Add one foot to the distance
Very Fast (10) Multiply the distance by .88
Tournament (11) Multiply the distance by .8
Tournament (12) Multiply the distance by .75
Championship (13) Multiply the distance by .7
Give it just a little more for an uphill put, and a little less for a downhill, particularly on Tournament and Championship speeds.