Guys, don't get me wrong I'm not saying split grade printing isn't a useful tool. I was just trying to put it in the context of the original post. What we had there was a print the photographer found to be flat at grade 2, but didn't require local adjustments like dodging and burning.
It may help to step back a little and think about what a split grade printing approach really is (actually the 0-5 split is part of a broader technique I'd call "multiple grade" because with variable contrast papers we can use any combination of filters to produce the desired print).
The original post is a good example here because aside from some edge burning, there were no additional local exposure adjustments (burning or dodging). Variable contrast paper basically has two emulsions, a low contrast layer sensitive to green light, and a high contrast layer sensitive to blue light. When light hits the paper, the more blue there is in the light relative to green, the more the paper's high contrast emulsion is exposed relative to the low contrast emulsion. This produces a higher contrast image. The reverse is true when there is more green light relative to blue light.
The variable contrast filters are used to modulate the relative amounts of green and blue light. A #0 filter passes mostly green light to the paper - hence low contrast. A #5 filter passes mostly blue light to the paper - hence high contrast. Light passed through a #2-2.5 filter contains roughly equal proportions of green and blue light, so that both the low and high contrast layers contribute about equally to the final image - hence intermediate contrast.
So, all we are doing with filters is getting the right mix of green and blue light to get the desired contrast level. Assuming the print requires only one contrast level for the entire image, there are two ways to get any desired level of contrast. One is to simply use the filter number that gives the right mix. The other is to mix manually, by splitting the exposure into two parts, and using the #0 and #5 filters.
Assume 5 seconds at grade 0 plus 5 seconds at grade 5 gives the desired print. All you've done is give the paper equal exposures to green and blue light (well actually you've probably given less blue exposure because the grade 5 filter typically cuts paper speed in half, but ignore that for the sake of theory). The grade 2.5 filter does this for you. It's the same thing. Suppose you wanted more contrast, yes you could try giving more grade 5 exposure and less grade 0 exposure, but you could also simply try a number 3 filter, which passes some more blue than green. And then you don't have to mess around with two exposure times and extra soft/hard test strips. Why not use one filter and one exposure?
The power of printing with multiple filters comes into play when different parts of the print need different contrast levels and/or when different parts of the print need different exposures. In situations like this it can be very helpful to break the total exposure down into different parts done with different filters. But if a given print doesn't require any such manipulation, and we are simply looking for the right overall contrast level, there is no value in manually recreating say a grade 3 filter by combining two exposures made at grades 0 and 5.
Apologies if any of this was repetitive or if various posters know this already. Just thought it might be worth taking a step back in the context of the original posted print/question.
Hope this helps.