Posted 2014-December-04, 09:40
I'm joining everybody. One of my mottos is "once you've decided your hand is X, it's X, live with it." The issue is that if you bid 4♠ now, then you're saying that 3♠ the last round was a mistake. And it might have been. But it might not have been, in which case 4♠ *is* a mistake. So, once you change your mind, you're guaranteed to have made a mistake; it's just a matter of which one (and if it is the former, you're giving them much more information to make the last decision).
Now, obviously, this does not supersede "re-evaluate your hand as the auction goes along." But here, absolutely nothing has changed - partner still has a 6-card suit and a weak hand, you're still white-on-red, they have enough strength to try 3NT if they have a spade stopper, which they do, ... So, you decided this hand was a 3♠ call because (one assumes) you have a shot at setting 3NT - which you certainly do if they don't have 7 minor tricks off the hoof to go along with the two major aces. If you didn't think you could set 3NT, then you should have bid 4♠ before. You chose not to, so back your judgement.
Now, maybe you only bid 3♠ here because either your area doesn't handle preempts well and 3♠ is often enough, or nobody else will push hard either, and you'll be going down one more than the field, or you haven't yet learned why you "preempt as hard as you're ever going to, the first time". Unfortunately, "maybe I can buy it for this" is usually a losing strategy.
When I go to sea, don't fear for me, Fear For The Storm -- Birdie and the Swansong (tSCoSI)