Is there any point in undersizing VARCHAR columns?
It does impact memory usage, especially when a client program has to allocate enough memory to receive a dataset. 

Bear in mind that a lot of apps (especially web apps) use UTF-8 which is a multi-byte character set. As such, you should really consider characters rather than bytes. 

If I was expecting over a thousand characters, then I'd actively consider a CLOB. I'd be thinking about whether it will store plain text or some form of markup (wiki / html ?), usage with non-Euro languages. The Questions and Answers here, for example, would be CLOB, but comments can fit in a VARCHAR.

If you max out a VARCHAR, then in six months someone will want to make it bigger again, and you'd be kicking yourself for not using a CLOB.