tapering is good to bring testosterone levels down in a controled fashion so you don't get to high of an estrogen/testosterone ratio (estrogen has a longer half life than testosterone so this happens if testosterone is stoped to abrubtly). Another reason is that the cortisol system adjusts best if you ease the dosage of testosterone slowyl. Stopping alot of testsoterone quickly will create a surge of cortisol activity. Also tapering has a good rep because alot of guys who don't taper forget that they continue to have high blood levels of test for several weeks after their last injection (1000-500mg of test will be out of the system much slower than 200-300mg of test). Because of this they mess up the timing of their clomid therapy, stop using antiestrogens to soon and lose alot of gains and get negative estrogen side effects.