You are absolutely correct in that the hormone combined with the ester has a half-life (most use 8 days for calculations), and I do agree that the average person will metabolize said drug at a fairly predictable manner. In fact, I posted some spreadsheets awhile ago using injection frequencies to determine the approximate ebb and flow of blood volume concentrations.
I am not disputing the fact that there does exist a simple logarithmic function in which we can approximate the total mass of the hormone after a specific time frame. What I am disputing is that the metabol
ic process in which we are able to process the depot and actually make it biologically active is not so simple.
There are many factors ranging from the condition of the CYP3A4 chain (essentially elimination pathway), a person's diet (this can affect absorption and elimination), value of SHBG (free testosterone is what we receive the actual benefits from), the mass of a person (if blood volume is greater, it will require more drug to reach the same concentration per volume), the location of the depot (areas poor in blood circulation will see a slower release of hormone), the ester involved (yes, TNE has a half-life of about 4 hours), and many other factors that modern science still is discovering.
If we were able to receive the same amount of hormones from one injection that a healthy male produces from day one, how do we address the fact that testosterone cypionate (and roughly enanthate) has a peak time of about 48 hours? Furthermore, steady state values require several half-lives (roughly 3.5-4), which is often when a person is able to quantify measurable differences.
*I am on my phone, so I'm lacking bookmarks to back up these statements from medscape/pubmed/journal of endocrinology. I'll try to dig up my resources when I have a chance to hop on my desktop, so you know I'm not just pulling numbers from my ass.

*
So while I acknowledge that there is SOME hormone in the bloodstream, and that there are even studies indicating a tripling of testosterone at the 48-72 hour mark post-injection, the odds of someone seeing eugonadal values within that time frame are very low. Unless we're talking ester-less testosterone as mentioned above of course.
I'll try to bring more facts to this tomorrow if still interested as I am getting the evil eye from the warden.. Er, my wife - as it's bedtime.