There are simply way too many doors I could open up and start glancing around in five minutes.
Really I'd personally like focus on about 3 different niches, just to give me more mental flexibility. If I get bogged down on researching 1 thing I can simply pull up a different tab and give my brain a quick break on that subject.
And I definitely do not want to overwhelm myself with too many niches at a time.
So one of the most important parts of doing freelance marketing, especially online is being keenly aware of which subjects and niches can really hang on to your attention. What draws you in? Those are the ones that you're most likely to do well in, because we absorb information 10 times easier when we find something interesting...something we're enthusiastic about.
If your studying a subject that really doesn't keep you, you want to ask yourself why you're even messing with it.
And maybe it's because an you've struck an amazing money making opportunity....for whatever reason.
If so.....than trudging through it all may be well worth it. But as a rule of thumb you want to turn your personal primary interests into your primary niches.