you don't need to use test in every cycle. I think some guru 20 years ago declared that and people started parroting it since. even Dan Doucheaine who is the biggest guru/parotter in the game says you don't need to use test in every cycle
when you use hormones your pituitary glands go dormant and stop producing LH, hence your testes do not produce testosterone on their own anymore. so your LH and FSH drop to 0. doesn't matter what hormone you use, its going to happen. and running test with your cycle doesn't prevent shutdown, this is yet another myth.
guys like to use test as their base because it is versatile, if you are running a compound that binds well with SHBG, the added androgens from testosterone will make your cycle better. you will up your estrogen and fill your muscles up easier with it. so its good to stack test with a dry compound to give it a kick.
having said all this I would never run something like primo, var, masteron, proviron, etc alone. you are just wasting them for the reasons I just mentioned.
something like deca, tren, eq, dbol, anadrol, etc can be run solo just fine.