Is it true that the "average man" produces 4-7mg/day of test, naturally?

I read the following and I'm not sure I get it. If it is 4-7mg/day then why would HRT consist of 200-400mg/wk? Isn't that high for simple HRT?

"In men 20-50 years of age, an intramuscular injection of 200 to 300 mg testosterone enanthate is generally sufficient to produce serum testosterone levels that are supranormal initially and fall into the normal ranges over the next 14 days. Fluctuations in testosterone levels may yield variations in libido, sexual function, energy, and mood. Some patients may be inconvenienced by the need for frequent testosterone injections. Increasing the dose to 300 to 400 mg may allow for maintenance of eugonadal levels of serum testosterone for up to three weeks, but higher doses will not lengthen the eugonadal period."