I stuck to my strategy pretty well during the race, but still had a couple of dark moments. When all was said and done, I'd guess that given my race day fitness level I left maybe about 10-15 minutes out on the course.
I think that there are two clear elements to your maximum potential - your actual fitness level, and the mental toughness you can maintain through the finish of the race. I think that your fitness level will give you the ability to finish within a very broad range of times, and your mental toughness dictates how closely you can finish near the top end of that range. I'd say that my strategy paid off well in terms of improvements over last year, and definitely stretched me, but I also have a lot to learn in terms of race day intensity and overcoming the fear of shutting down. When you don't know how your body will respond under that kind of loading, I think you tend to get conservative and start to doubt that you'll still finish if you go faster or just maintain pace. The pain becomes fear of not finishing. Race experience is the most valuable tool in stretching those threshholds, and this was a great race for me in that regard.
In terms of actual physical fitness and race planning, I could tell almost exactly what I didn't do enough of in the off-season. I didn't lift weights nearly enough, because my leg power wasn't what it was last year, and I know I could benefit from that going into next year. I got small this year, and that paid off in terms of giving me less weight to carry around the run course, but I missed the power on both the run and the bike that you need to really power through wind and keep those legs swinging during the run. Nutritionally, I was surprised to have some issues with my Infinit around mile 60 and on. I under-hydrated last year, and I think I may have done the opposite this year. I was burping up fluids for the whole second half of the ride, and just had to keep swallowing it back down. I might have actually been better off doing some solid foods at the front end of the bike course, and then switching to fluid only nutrition at the midpoint. That was a first for me, so I'm going to have to go back to the drawing board and expirement in the offseason with some solids. I wouldn't say it was a huge deal, but I did have to pull back on my calorie intake over the last 20 miles of the bike, which may have hurt me at the end of the run. The Clif Bloks on the run...... I ended up doing the same. I just couldn't take them on schedule after mile 16. I was doing one every 7 minutes, and had to change that to every 14 minutes because they kept coming up. They tasted just like the infinit - super sugary. All in all it was a great day and another huge learning experience for me. I hope the Ironman learning curve stays steep for a couple of more races, that would mean that I could actually have some more big improvements in the future and maybe one day have a shot at Kona.