The hypothesis is that daily peak serum testosterone levels play a role in the benefits we get from testosterone. If true, then with daily injections you may not want a long half-life if you're exploring very low doses—because you get more bang for the buck if testosterone goes up and down each day, as is natural in young men. In this respect it's useful if your apparent half-life for cypionate is really only 1.5 days. In contrast, I absorb it more slowly, with an apparent half-life closer to the nominal five days, and thus would see little serum variation with daily doses. Even if we were otherwise the same, at the same daily dose you might for example peak out at 700 ng/dL and have troughs in the mid 400s, whereas I would be mired in the low 500s all the time. To attain the daily variation you see I need to get some of my testosterone from propionate.
