I now work with a financial institute where they took the decision NOT to use date formats for data-values. This meant that they use 20110310 to indicate the 10th March 2011. It was possible to use a date format but it was decided to use a numerical format.
Everything goes at a cost. Likewise, misusing a numerical format to store a date value also has its costs. In principle, it is possible to store 20110254 value. It is numerical but this can not be used to store a date. The date 54 February 2011 simply does not exist.
The organisation uses SAS to handle the data. Hence, we need a SAS expression to check whether the numerical value can be used as a date or not. This means that 20110254 must be seen as a non-sensical date value, whereas 20110310 does make sense. The SAS expression to check the validity is: input(put(input(put(EFFECTIVE_DATE, 8.)yymmdd8.).
What is lesson to be learned?  use date formats for a date.  never/ ever think about using a numerical format.