Helmets are designed to shatter. Read the label in the helmet. They are only good for one impact. Some will even provide a free replacement with proper impact documentation.

Caffeine is not different than loud music or other stimulating activities. Caffeine just attacks at a chemical level. One serving a day should be your max and best in the AM. Read about the metabolic path of caffeine. Same for alcohol. MSG is just as bad.

Recovery is not about the amount of rest. Recovery is about reducing the peaks of activity and stimulation. 23 hours of low stimulation activity is worthless if the 24 hours is high stimulation activity.

Recovery comes from continuous periods of moderated stimulation and reduced symptoms. Every time you get over stimulated or push to fatigue, it is like you have to start recovery all over again. Just delaying recovery. Not increasing the magnitude of the injury.