Interesting stuff… I haven’t really got the practical application of the chart for planning my race strategy either, but is applying it to my past result the way to do it?
For my race in the summer, my bike split was 5:45 with a IF of 70% and a TSS of 284. If I am interpreting the chart right, I was in the “good range” i.e. dark gray. This checks out because I was able to run continuously during the marathon (ignoring that I went out way too fast 
) and ended with 3:57 split.
So can I draw any of these conclusions for future races?
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I could ride at a higher intensity, say 71%, accumulate a similar TSS, thereby going faster and still be confident I can run a similar effort of the bike (albeit at a more even pace)
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Instead of inputting IF into best bike split, it would be better to put in TSS to get a bike strategy
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I suppose both of those are the same question, can it be boiled down to… for future races should I always aim for a TSS of 280 ish, knowing I can run off that?