I started by falling into the normal trap: what do the professionals do? Obviously they're fast, so why shouldn't I just do what they do? Well, this was long before I became a coach and really morphed into a student of the sport. Imitation of success seemed like a better method than trying stuff at random. What I came to understand over the years was that professionals can do a lot of things age-group athletes can not. Their entire job is to train, recover and race. They have the time to train 40 hours in a week because they have the time to recover from 40 hours of training in a week.
They can also do the stretching, massaging, chiropractic sessions, and strength training that most of us don't have the time for in addition to our day jobs. The pro's can handle more extreme positions than the average person.
My first experience in the wind tunnel was in Colorado. Mark Cote ran the MIT wind tunnel before moving on to Specialized where he designed their Transition and Shiv triathlon bikes. He was the expert running my session and the first thing he did had nothing to do with aerodynamics. He put me on a fit bike hooked up to a power meter. My original bike position was duplicated and they did a brief heart rate/power test. Then the position was changed and the test repeated. Then again with a 3rd position. The first step in finding the best position was seeing how they affected my heart rate and power. If something is more aero but makes it harder to breather and elevates your heart rate... is it actually going to make you a faster triathlete?
Overall: the most comfortable position was the fastest for me when I was doing long course racing. And the most important lesson I learned from Mark: “for me”. Everything we had tested, conventional or not, applied to me, but the same can't be assumed for anyone else. The most important thing to start with was what was most comfortable and most powerful. After that, unless you're actually testing in a wind tunnel, it is just a guess when it comes to how aerodynamic a position might be. We tested a number of different wheels, helmets, water bottles, and even trimming my beard. All of this I still apply to my setup today. But when it comes to fitting a triathlete to their bike, never compromise what feels good for what you assume might be more aerodynamic.