Many Fortune 500 companies rely heavily on custom-built applications and have a large internal IT department of their own.
They generally tend to build their own standards and naming conventions. This helps bring large development teams on common grounds, and it is very easy for any person on the team to understand as well as reuse code.
These companies enforce naming conventions and standards through walkthrough.
Many other companies rely entirely on the standards recommended in the documentation that comes with a development tool. This is also a very effective, fast, and cost-efficient way to build standards for your applications. Companies that outsource their IT efforts generally seem to adopt this approach.