Transdermal patches (adhesive patches placed on the skin) may also be used to deliver a steady dose through the skin and into the bloodstream. Testosterone-containing creams and gels that are applied daily to the skin are also available, but absorption is inefficient (roughly 10%, varying between individuals) and these treatments tend to be more expensive. Individuals who are especially physically active and/or bathe often may not be good candidates, since the medication can be washed off and may take up to six hours to be fully absorbed. There is also the risk that an intimate partner or child may come in contact with the application site and inadvertently dose himself or herself; children and women are highly sensitive to testosterone and can suffer unintended masculinization and health effects, even from small doses. Injection is the most common method used by individuals administering AAS for non-medical purposes. 
Fortunately, we can look to longitudinal training studies that actually measure muscle hypertrophy for answers. It just so happens that my lab carried out a study that sheds light on this very topic. We recruited 17 resistance-trained men and randomized them to perform either a bodybuilding-type (3 sets of 10 reps) or powerlifting-type (7 sets of 3 reps) routine. The per-set TUT for the bodybuilding-type routine was about 30-40 seconds while that of the powerlifting routine was around 9-12 seconds. Training was carried out 3 days a week for 8 weeks.