Testosterone is significantly correlated with aggression and competitive behaviour and is directly facilitated by the latter. There are two theories on the role of testosterone in aggression and competition.  The first one is the challenge hypothesis which states that testosterone would increase during puberty thus facilitating reproductive and competitive behaviour which would include aggression.  Thus it is the challenge of competition among males of the species that facilitates aggression and violence.  Studies conducted have found direct correlation between testosterone and dominance especially among the most violent criminals in prison who had the highest testosterone levels.  The same research also found fathers (those outside competitive environments) had the lowest testosterone levels compared to other males. 
Test-P injections are made as a rule every day or every other day. Steroid cycle lasts 6-8 weeks. Testosterone enanthate and cypionate cycles shall be run not less than for 10 weeks. On shorter cycles long esters will not be able to expose their full potential. For enanthate and cypionate is one injection every 5-7 days is enough. However, some athletes prefer more frequent injections in order to provide more even hormone level in blood and to avoid dramatic fluctuations. And don`t forget, that steroid aromatizes very easily to estradiol. Independent on the compound you use, keep your estradiol under control by taking aromatase inhibitors (anastrozole preferably). Antiestrogens (SERMs) are in this context not recommended, because they will reduce the cycle efficiency.
The partition coefficient of the ester in question is important because is effects how long the drug itself stays in the system. If the testosterone transfers too quickly from the oil to the blood, the result is a sudden spike in testosterone which then rapidly drops once the dose has been used up. In the example of free testosterone injected into the muscle from a water suspension (as in Aquiviron, mentioned above), the testosterone is essentially immediately available to the bloodstream due to its low partition coefficient, and thus there is an immediate spike of testosterone which is used up quickly in the body.