I think there are plenty of people that have tested various stimulants and know the effects those substances have on them, but who don't know the exact half-life of the substances.
I'm not even sure whether the real half life of caffeine is the thing that matters. When it comes to designing drugs there are quite a few things that are done in the delivery mechanism of the drug that can effect half-life.
Pharmacokinetics (half-life and other variables) of drugs and their different delivery methods are public knowledge, there are individual differences in metabolism of course.
When it comes to designing drugs there are quite a few things that are done in the delivery mechanism of the drug that can effect half-life.
For most drugs the elimination half-life is so long that a faster route of administration makes minor difference. For caffeine for example it's about 4.5 hours. You can shorten the absorption from < 1 hour to seconds but that probably won't ...
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