[hahamrfunnyguy]

100% - The #1 developer mistake is not knowing when to ask a co-worker for help. Juniors make this mistake more often, but I've observed the same pattern in developers with lots of experience too.

When to ask a co-worker for help: domain specific problems, open ended questions, subjective questions that would be hard to input into a search engine, etc.

Ask questions when you would spend a lot of time tracking down the answer. Don't ask a co-worker a question that a web-search could answer quickly.