Will a prime-time television slot always guarantee an advertiser the best results in selling a product?

When it comes to any type of advertisement you have to keep in mind the demographic of people that you are marketing your product to. For instance, if I were selling a new line of Golf clubs my best bet would be to advertise on a golf channel, or at least some sports channel. This makes sense because the majority of people who watch the Big Bang Theory probably don't play golf, but those that watch the golf channel probably do have an intrest in playing. Remember that prime time slots are filled with shows that appeal to the majority of everyday people, so if a product appeals to a large variety of people then a primetime slot may be the best choice. I hope this helps.