I've come to the realization in my short career that 90% of my time will be spent on activities that produce 10% impact and 10% of my time will go towards activities that have 90% impact. But the 10% time producing 90% impact stems from the fact that I spent the other 90% doing mundane work and understanding the environment/product/whatever problem am working towards solving.

As an example, my company uses Django and the first 6-8 months I have spent hours debugging what would be a stupid issue like misconfigured Django or missing url. Eventually, that led me to optimizing the version of shell_plus that my company was using improving its bootup time by 200%(this was a rather large codebase). That's an instant 200% gain per developer/per django shell load and is probably the most impactful thing I've ever done. We estimated it would save around 6.67 hours of developer time per day(2 minutes saved - was originally 2.45 * 200 developers * 1 shell load every day)