Just found this tip, can any experienced users verify it's correctness?

"There is a rule of thumb that I have come up with when using a plasma cutter to achieve the best cut. You won’t find it in any plasma cutting manuals though. I have found that 20 amps is truly the lowest practical limit for a plasma cutter. That amperage is good up to 1/8” of an inch. After 1/8” you can typically add 10 amps for every additional 1/8” of cut. While this isn’t perfect for all conditions, it works well as a general guide. For 3/8” cut, 40 amps works out well for most brands of plasma cutters. For ½” cut, 50 amps works out well, etc. Keep in mind this isn’t the maximum thickness of cut that a plasma cutter is capable of cutting but rather, it is a good rule to follow for decent cutting speed and quality. For most torches, various tip sizes are available, each with its optimum cut range."