Do you need a specific niche to be successful in photography? Probably yeah. Guess that’s why I’m still working as an engineer. 😉
Jokes aside I think it depends on how you define success. If your goal is to earn a living taking family portraits, or to shoot weddings, or cars, etc… then yeah of course it makes sense to focus on one subject type. Think of it this way: if you were hiring somebody to take pictures of the launch of your brand new car then would you go with someone that can present a well organized and edited portfolio of car pictures or somebody that shoots butterflies, and cigarette butts, and the occasional car?
If you made it this far I’m sure your thinking ‘Good Job, you’ve managed to define the difference between a hobby and a career.’ – Yeah that’s a pretty accurate assessment. But I’ll leave you with one additional thought: You don’t want to have a portfolio of all red cars and then leave potential customers wondering… “Can they shoot a blue car?”
So yeah, pick a few areas you’d like to focus on and build a collection of photographs to the best of your ability in those areas. But make sure you take plenty of pictures of blue cars along the way.