Your average consumer won't make the financial commitment to a product for more than 4 weeks. We are not the average consumers on this board.
4 weeks is a very short period of time in relation to training and seeing results in general. Now, with a test booster, or any performance enhancing supplement, you're asking to see results immediately and it probably isn't going to happen. Most scientifically proven periodized programs are broken into 4 week mini-cycles. Some are 6 weeks. I'd venture to say that most test boosters are going to be best utilized doing a 6-8 week run of them. If someone isn't willing to make a purchase for 6-8 weeks then they probably aren't going to be willing to spend enough money on foods and nuts and bolts supps like bcaa, creatine, vitamins, etc... to get proper results that will be maintained AFTER the cycle anyways.
That said, I'm currently just starting week 3 of D-Aspartic acid and I noticed improvements in about 5-7 days. After 4 weeks on DAA, I'm switching to PNI's new DAA product Paragon for another 4 weeks. I've had some people at my gym (about 6) try Prodigy and they love it, claming they are feeling/seeing effects in as little as 5-7 days.