I realise my split grade print remark may seem tangential to the discussion of test strips, but its not really, as I was thinking of taking test strips to a grid format. What I mean is that you do a grid of exposures, varying the amount of grade zero in one axis on the paper, and grade 5 in the other direction, so that you end up with say 25 different combinations. You have to do this a couple of times to work out the envelope of sensible exposures. It does mean you use more paper, but it also means you nail exposure and contrast simultaneously. However, I was doing this with a PCS2000 enlarger with remote control of pure blue and pure green light (hard and soft), and now I have switched to using a LPL 7700 which doesnt allow this with such ease (you could do it with Ilford under lens filters).