I think the more you use a mandatory preview, the less notice people will take of it. At the moment, limericks is marked out as special, which I think is probably right.
(Projoy) This is probably true, but at least there's a chance one will notice an error. I'd be in favour of a mandatory preview, and I nearly always preview anyway. It's little bother.
Well, clearly we should then have mandatory preview on every game, and double preview on limericks. In fact, why stop there? The number of previews in a given game should be a parameter to be set at the beginning, based on the importance of avoiding error.