The Thing with... Duration cards.
Not a long article here, and I don't think this is ground-breaking or earth-shattering to lots of people, but it needs to be out there.
They miss reshuffles. Much more often than other cards. Because not only can they miss the reshuffle if they're the last 0-4 cards that don't fit in a hand, but they can also get caught if you played them the turn before your hand draw triggers a reshuffle. As your cleanup drawing is usually at least a very significant portion of the number of cards you draw... anyway, they miss the shuffle a lot more often.
This effect is further exacerbated by card-drawing durations. Outpost, tactician, caravan, wharf, haven, we're looking at you. In fact, I'll go so far as to say that one way or another, for much of the game anyway, tactician USUALLY misses the reshuffle. Engine play also make this worse than it is for big money, because you're cycling more, reshuffling more, and therefore missing that reshuffle more. Of course, missing a reshuffle in general is less important in an engine deck, because you do cycle more.
Similarly, though, these cards will collide less often. Particularly this is important for terminals - you can buy more terminal durations than you can other cards, because they're less likely to collide, because one will be out (often having missed a reshuffle).
So, their effects are generally more powerful than those of 'normal' actions, seemingly, because you get to play them less often. The effect is spread out over two hands, which makes it more likely you get to play it only once every two shuffles. If they ALWAYS missed the reshuffle, the one-turn power of the cards could be comparable to 'normal' cards. As is, they're a bit weaker, because they don't miss THAT often, but at the same time, twice something that's a little weaker than normal, and they're still typically strong cards.
You also want to note that the balanced-looking effects aren't actually balanced (mainly I'm talking merchant ship, caravan, lighthouse, and wharf here; it's biggest on MS and wharf). The second turn is much more of a boon than the first turn, because on the first turn you have to spend an action and a card in your hand playing it on the first turn, and you don't on the second. So caravan is a cantrip now, lab next turn. Wharf is moat with a buy now, smithy with a buy next turn. Etc.