LOL. When I look to assign low rates to modern models I dig out my old 1970's Contender 60 manual and check out the rates.

Aileron: low 3/8" up/down, high 5/8" up/down
Elevator: low 3/16" up/down, high 5/16" up/down
Rudder: low 5/8" left/right, high 1" left/right

Nowadays if you don't have 2" in any surface you ain't jack spit.

And this is on a 60 size model that used to be considered a hot performer! I use the highs listed above as my default lows for .40 and .60 size models if the instructions seem a little crazy to me. I don't care what model it is there are days when I just want to fly it smooth and in large, expansive maneuvers. What you can do is copy the model settings (if your transmitter has the feature) and rename it, then tone it way down. That will be like having quadruple rates on a model. Trouble is you can't go from mild to wild in a single flight.