I've found it to vary greatly.
My first job was a result of me contributing to the company's OSS projects for about a year, so I was already productive.
I had a very brief stint at a startup where I spent little over a week and got nothing done, because I could never get comfortable with the codebase.
At my current job at Navana Tech, I inherited a working-but-also-broken codebase from someone who was no longer an employee, and hadn't done a particularly good job at making it easy to onboard new people. This cost me 4 days of picking apart things to get a sense of what I am building and how to go about it. Been breezy ever since!
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