First Strip: 5, 10, 15, 20, 25, 30, 35, 40
Second Strip: 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5, 35, 37.5, 40
For example, if I learn from the first strip that the window I want to be in is between 20 and 30 seconds, I'll run a fine progression in that window. And obviously, there's no need to run all the times on a test strip if you know they are out of range. Notice how the progression (intervals between doubling of exposure) become more defined as you approach the working zone.
I also give credit to those who can invent new methods for progression, whether it be by f/stops, doubling of time, logarithmic, a gut feeling, etc. If it produces the results you desire, that's what counts.
Oh, the Kodak book is titled: Bigger and Better Enlarging in Color and Black & White (ISBN 0-8174-0579-8)
Another book that I have really enjoyed, and also describes the progression that Mr. Adams wrote about: The Craft of Photography by David Vestal (ISBN 0-06-014497-1) In this book Mr. Vestal demonstrates using entire strips per exposure test. Not very conservative, but very revealing.