What is the 20% that a junior engineer can do to have 80% of the impact on their career?

The biggest thing at your level is just learning the process and making sure you regularly deliver code. Twitter is going to be one of those places likely to be a bit tougher on you because of Musk owning it, but interns traditionally are just thought of as an investment that pay dividends a few years down the road, but not typically immediately. Besides that, get really good in the stuff you like doing and that will catapult you forward quicker than you could have done otherwise.

Something you can do as a junior engineer that only takes 20% of your time even if you have to change jobs to achieve it is to choose the right team/company for you that has the right people, pay, purpose, tech stack etc so that you thrive at work and enjoy software engineering and your life.

At your current job it is important as a junior engineer to give feedback to your manager to find problems that:

1. you can solve in a reasonable amount of time
2. but also keep challenging you and pushing your technical understanding
3. and that you genuinely enjoy thinking about and ideally even get energy from working on

I have an actual, tactical 5-minute thing that will majorly boost your standing as engineer, especially as a junior: Get into the habit of making test plans. You should already be testing your code anyways to make it sure that it works before submitting the pull request - Doing test plans literally just means that you are recording this process and attaching the proof.

Despite the simplicity of this trick, I have seen so many engineers not do this, even senior+ engineers at big companies. It won't boost your career by 80%, but it will still help quite a lot, especially when considering the very tiny time investment that's needed.

If you want that full 80% boost (again, especially as a junior), check out my code quality course: [Course] Level Up Your Code Quality As A Software Engineer

If you want to go even deeper, check this out: "What's the core insight behind quick growth?"