One interesting thought came after I read the point 8:
Software systems and software products each typically cost 3 times as much per instruction to fully develop as does an individual software program.I immediately thought about that old estimation rule: estimate how long it will take to be done, and then multiply it by two. I always though it to be unserious or a manifestation of intellectual laziness. What, you aren't able to say how long this effing program will take to be written? Just sum up the parts (as shown below)!

So maybe we should take the above citied measurement data, at use it when estimating? Just multiply our technical-only estimate by the "real world" factor? Personally, I still cannot believe that the "real world" factor be so high as 3! Am I too optimistic? But I think that frw=2 should be a good choice!
Although I'm a little afraid here, as I always imprement a given piece of code faster than my own PERT estimate. But recently, when estimating the entire system, I missed the point completely: new requirements, unexpected dependencies on not so great libraries, the internal pressure to please the customer... This all sums up in a greater project! An at that point I should have been to muliply so high as by 4! Welcome in the real world.
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* Harry W. Boehm, "Industrial Software Metrics: A Top-Ten List", http://csse.usc.edu/csse/TECHRPTS/1985/usccse85-499/usccse85-499.pdf
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