Even computerised we find that the average test time is still the same at around 45-50mins. What can make big difference is your catchment area. We are in a fairly affluent area and many of the vehicles we see are fairly well maintained late models, untroubled by corrosion etc. If you test a lot more vehicles at the less desirable end of the scale, there's more to worry about, even recording the defects takes longer. One thing we found, when we stopped price cutting some years back we saw less vehicles at the bottom end of the scale.