FROM THE STICKY TRT PROTOCOL FOR INJECTIONS BY KSMAN...
Injecting testosterone once a week induces spikes in testosterone levels followed by lows. This can make many feel bad or worse at the end of the week than their pre-TRT state. As time goes on the dead zone gets wider and they feel no relief with injections. These feel much better injecting twice a week or even EOD [every other day].
Injecting every 2, 3 or 4 weeks is horrible. You need to self inject and inject frequently. With frequent injections the volumes are very small and one can inject in the quads [vastus lateralis] with #29 0.5ml 0.5" [50iu] insulin syringes.
These are slow to load but injection times are reasonable as the small plunger diameters create very high pressures. Do not use 1.0ml syringes. This same size syringe can be used for hCG injections, which are also SC.
EDIT: Injecting EOD [sometimes written as E2D] or E3D [every third day] can be a difficult schedule. You can set up reminders or appointments in calendar software, such as MS Outlook, for E2D or E3D etc.
Small needles will reduce muscle damage. Some use #25 1" needles, but this may not be any "faster" than the above 50iu insulin needles.
You do not need to inject into your gluts with 1.5" needles!
Canadian clinical research has demonstrated that TRT by SC [under the skin injections into body fat] produce steadier testosterone levels and improves sense of well-being. Feel free to find out what is more comfortable for you.