I agree that you almost have to force it to have DMS linger. I boil hard only the last 10 minutes or so of the boil, with the cover off, the rest of the time its 75% covered boil at just above a simmer. I have had judges search for DMS and call it out when it isn't there (such as with an American Premium Lager using adjunct). One said I needed to boil longer. Oh well....BJCP judges aren't infallible. (Yes, I am one.)