because test suspension is water based and absorbs into your system very quickly you can inject it multiple times per week into the same muscle. downfall to this is that you will build up scar tissue much faster in that muscle from the higher amount of injections.
it is a very painful injection because basically in a nutt shell what happens when injected is the water is immediately absorbed into the muscle tissue leaving the steroid crystals to sit on your muscle which irritates the hell out of them. oil based suspension is actually typically called test-no ester instead of suspension since it is not suspended in water like the water based product but oil. it may give a slight repreive on the pain but not much and will still hurt quite a bit.
suspension should be injected 2-4 times per day due to the very very rapid absorbtion raten at which it enters the bloodstream and goes to work. half life is approximately a few hours so if only injected once per day you would only have it at work for you for a very short amount of time.