Algorithms

While looking for a job I went on an interview which was focused on my ability to come up with solutions to algorithmic problems, and fast. The interviewers were sure it is the essence of the job (job title read: Senior C# Developer). I have always believed, my job is to create architectures that last and -- among other things -- I do like patterns that make algorithms unimportant, interchangeable. From my experience, it's rarely even required to optimize algorithms, and I never do this until a performance impediment arises (which is also rarely the case).

What's your take on this? Must a good software developer be fast and efficient when creating algorithms -- or is it more like a nice-to-have-but-not-necessary thing? (The answer may depend on the specifics of your project.)