In reply to Dale Thompson.

Thanks for writing. I welcome diverse opinions. I agree with what you say: what one programmer sees as "unnecessary" might be a necessary defensive technique for someone else. I know a good programmer who puts
RUN; QUIT;
after every SAS procedure and DATA step. Another programmer constantly puts (unnecessary) parentheses around the logical statements in IF-THEN/ELSE clauses. I understand why they make these choices.

If you search the internet for
SAS defensive programming techniques
you will find many tips and techniques for defensive programming in complex production routines. Some of them are rather clever.