My experience doing this for several large companies at a time is that the questionnaires don't really go away with certification. There are probably some shops where audit reports will substitute for the Excel spreadsheet Q&A's, but there are plenty of others where the Q&A is a dealbreaker part of procurements no matter what.

If you're in a line of business where your customers have questionnaires, just plan on having someone whose job is to fill these things out.