I don't think so. A program is an infinite stream of jobs and is never quite 'done'. The less time you spend on keeping things nice and clean, the more frequent the jobs will be. After all, it still needs to be maintained.

Unless you are using a library, it's gonna be better long-term going for complete understanding. Even then, it's usually a great idea to understand what a lib does under the hood.

I guess it depends. A freelancer hired through oDesk by default has a clearly defined job and zero incentive to care about ‘nice and clean’.

Sometimes I just can't help thinking that the code I maintain has been optimized, foremost, for someone's job security—even when I know that the author is actually just of ‘get-shit-done’ type, and has been paid hourly.