I would say that anybody who claims that testosterone doesn't shut you down is off their nut.
The reason I advocate using testosterone in every cycle is that testostorone does more in the body than just build muscle. Keeping some testosterone ensures that all normal body functions are covered.
Libido is the best example, Early in my AAS career I ran a 6-week cycle of b-dol alone. I had zero libido from week 3-9.
Primo is another great example. Scheering (the manufacturers of Primobolan) conducted a study long ago using primo in place of testosterone for HRT. They found that those on primo had much lower estrogen levels and reported loss of libido (and enlarged prostate). Should have been perfectly predictable since primo doesn't aromatize to estrogen and low estrogen is known to kill libido.
So I guess if a man really don't care amount maintaining a sex life, it might be alright to design a cycle without testosterone. But how many men would fall into that category?
agreed, and i also think this is the more common view on why to run test every cycle...