As someone who has never really programmed in a group, what are some examples of common scaling issues?  I typically try to adhere to the principles of loose coupling, pure functions &amp; immutability, clean &amp; readable syntax, &quot;don&#x27;t reinvent the wheel&quot;, algorithmic optimization before code optimization, version control, unit testing, etc.<p>But I&#x27;m curious: what useful principles have other HN users acquired after decades of programming or working on giant projects that a &quot;solo programmer&quot; like me might not be aware of?