.< Every writer uses Tropes. Tropes are like an iPhone ad "Want a story about a guy having to save a girl … theres a trope for that. Want a story about a lost hero trying to find his way home in an unfamiliar setting theres a trope for that too."
Tropes are merely the consolidation of common stories to their base ingredient and then given a title to easily refer to them. However each story is inherently different by simply how the author decides to tell it - even when an author tries to tell the opposite story of a common trope there is already a trope for that. Oda doesn't need to spend time researching tropes he has enough imagination he is re-inventing tropes well enough on his own I would assume, TVtropes exists for others to get an idea of which forms of entertainment share common tropes you might be interested in and then you can see the same one "Find the mcguffin to defeat the big bad" shown a thousand different ways.
yep. thats what im basically trying to say in a nutshell.
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He uses his own tropes.
tropes are like that, you can modify them to appear unique. but its still that.