I read this interesting paper on this very thing just the other day.  The paper said in regards to STB and naptha that you need to get as much as you can in the first pull.  That's where it is white and reflects light etc.  It said later pulls get progressively yellower.  Say you did 1 pull a day.  The first is going to be cleaner than the second.

What I took from this is that if you aren't going to clean up, or say you want those fats etc. you have a timeframe.  First 1 day pull is where you get product that twinkles.  Last pull day is where you get yellow goo "earwax".  So spread out over 4 days you see that progression.

The moral of the story on that paper was to use measurments that really take advantage of that first pull, using your requirements, and that will most likely get the most from the stage 1 side of the 4 days you're given as opposed to the stage 4 side of what you can recover.  The paper said after that 4 days your naptha costs cut you off from further funding.

Ironically they used the same ratios that can be found in the faq.