Unfortunately, not everyone who works with, talks about, or advises on testosterone is genuinely knowledgeable about it. Yes, there are many doctors who discuss testosterone yet know nothing about it. For example, it has a half-life of around 7 days. That means that in around 7 days, half of the drug will be out of your system or will no longer be acting on you. So, if you're at 1000 on Monday, which is shot day, you'll most likely be at 500 the following Monday if the math holds.