Most businesses you want to work for will also develop libraries/frameworks that are used in house. Or they might develop applications which consist of more than just plugging libraries together.
You will develop code you reuse, you may even pack it into libraries, however you shouldn't be thinking this is a fundamental process of the business. It's a side effect that makes some things simpler when you do similar things repeatedly.
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I think the first poster is spot on.
Most businesses you want to work for will also develop libraries/frameworks that are used in house. Or they might develop applications which consist of more than just plugging libraries together.
You will develop code you reuse, you may even pack it into libraries, however you shouldn't be thinking this is a fundamental process of the business. It's a side effect that makes some things simpler when you do similar things repeatedly.