They all do it differently, because individual developers have taken it upon themselves to "roll their own" without consulting with the team about best-practices coding standards and what we already may have, or not have, to work with. A lot of times you’ll work in a shop where various contractors are brought in, and nobody takes the time to explain “how we do it here”. Not only that, since they know they won’t be there long, their sense of responsibility to the overall success of the project is reduced. Why did they do it? Simple. Management doesn't necessarily think that coding standards for the development group are that important. They're wrong! I know, because I've been in these environments enough times to know the difference, and I have been a manager too.
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