My test strips follow this progression: 4, 5.6, 8, 11, 16, 22, 32, 45.
This gives a nice even progression of 1/2 stop at a time.
I alway use 10-13-16-20-25-32 which gives 1/3 steps. I count with the motronome and use only whole seconds. (o.k I could count one-and-two or even one-and-the-two to divide seconds, bit I don't bother with that)