The referenced paragraph is for performance testing of welders, not procedure qualification.
Paragraph 5.4.2.5 (applicable to procedure qualification) says exactly the same thing, but no thickness ranges are given. I believe it was intended to have the same thickness range listed in 6.2.2.e.3 (see 5.3.2.3).
This was a long way of saying that I believe your interpretation is correct.
BTW, I am looking at the 19th ed, Sept. 1999.
Charles