varchar2 ? Is this an Oracle question? This is a Microsoft SQL Server Forum.

In general it is proper practice to choose the appropriate data type from the outset. It is fundamental to the success of a database in terms of performance, longevity and feeds into maintenance costs as well.

I am not sure about Oracle internals but in SQL Server there is a penalty for using a wider column than necessary in terms of memory allocations for space where data will never reside because the column is always far wider than the maximum expected data lengths.

Again, in general, anyone proposing to use a wider datatype than is necessary "just in case we receive wider data later" should not be influencing data modeling decisions.