Besides the "one more trick" thing, regards to the "waste of bids" question, there is also the question of "what else would you propose using the bids for?". With good hands typically you want to save bidding room for exploring game/slam options, so normally you'd want these preempts to be "bad" hands, with safety from playing strength provided by the long good suit. a) People who open on 5 cd suits are just going for greater frequency at the expense of greater risk. You pick up 5 cd suits much, much more often than 6 cd suits. Bidding over preempts is harder than bidding over passes, by preempting more often you give the opps more opportunities to misjudge. The greater risk is when you don't catch partner with support, and go down (doubled or not), with the opps not making anything, and occasionally when your preempt pushes them into some making game or something that they probably wouldn't have bid otherwise. With 5 cd suits your losses from penalties will be greater and more frequent, the question is whether your gains when the opps misjudge offsets this or not. 3rd seat favorable I would expect 5 cd preempts to be fairly frequent even from normally conservative players. Bergen disciple players would open 5 cds frequently in other vuls and seats. Six card 3c preempts are somewhat common since weak 2 clubs isn't available. If you are playing 2d as multi or flannery, that would also increase 6 cd 3d preempts. But since 3 level is higher, with greater risk, people who are frequent 5 cd weak 2 openers don't necessarily open 3 with 6 cd preempts, many open 2 with both 5 and 6 cd suits (can use responses to 2nt to clarify). b ) Unlike the extra trump in a long suit, which is often worth a full trick declaring, the extra trump in support is not worth a full trick, only a fraction of a trick. It can get you an extra trick from an extra ruff you might get, or making bad split less likely, saving you from a bad split, enabling some elimination and throw-in in the play. But this only happens a portion of the time, not all the time, thus only a fraction of a trick. And less often when you are balanced. The 4th trump is worth a point or two when unbalanced, and should cause you to promote borderline single raises into limit raises (9 hcp, good 8, with 4 cd support + stiff), but not with a balanced 6 count. Also some people play "Bergen raises" where 4 cd support of 5 cd major normally makes a 3 level raise (jump raise = weak, 3c/3d used to show other ranges, another possibility is jump raise weak, use 2nt as LR+), though this is usually avoided on a flat 6. Balanced 8/9 is a different matter.
