That’s very dumb.

You so know that choosing an injecting site is dependent on multiple factors, of which is key, the amount of drug to be injected and the pharmacokinetics of the drug and how it is metabolised.

Testosterone is a anabolic/androgenic hormone. It is absorbed by androgen receptors. Your deltoid has androgen receptors, but not as many as your quads.

So, when injecting a small amount, say up to 100mg, the deltoid is fine as a suitable site. When injecting more than that, a bigger site with more receptor’s is required, like the quad.

It’s not just about mg if testosterone. The volume also matters, a small injection site can’t take more than 1ml, regardless of mg. For anything above 1ml, the quad or flute is best.