Still waiting on my copy of the Keith Tanner book...got a tracking number and watching it crawl across the coast.
My .02 cents worth...
The average guy struggle in bursts of work and head scratching, picking up a part here an a part there and modifying it accordingly. Almost everyone unless they buy a kit or "systems" (suspension, brakes, wiring, or body) will reach a point when their experience needs to be broadend.
"Damn it I knew I was going to use THIS hand brake I could have weilded this bracket or asembly during the chasis build."
If you knew you were going to use a live axel or IRS you could have prepared for it in advance.
Now if you built several cars you can do it in a fraction of the time as a first time scratch builder. Why? because you know the road ahead, you know the bottlenecks, and you know how to plan for things in advance.
Keith Tanner has built Miatas and sevens but if you told him to build from scratch WITHOUT USEING MIATA PARTS he could still buildt it faster than most of us. Sure he would have some head scratching moments on spindles and other parts....but it would be a fimiliar road he has already traveled.
Experience is the greatest factor, what works and what doesn't, where can you make time without having to redo or backtrack on your work.
My guess is there is a 100 ways to skin a cat, if you could think of 35-50 you would be a freaking genius. The other 65-50 ways you would have to learned buy doing, talking to the old hats, and redoing it time and time again.