Other People’s Messes
We're comfortable writing messy code when it's just ourself who will see it. If you know others will at some point review it, it's best to clean it sooner rather than later.
For Cleaner Code, Write Ugly Code
When prototyping code, make it ugly. Generally speaking, the number of iterations correlates more closely to success than the total time spent. This way, you are forced to go revisit your code, streamline and beautify it.
Knowledge Resides In Teams
The "magic of a gelled team is that they know how to work together". The responsibility of a team's manager is to understand the inter-relationships that create that magic.