If you open $4/$3 and your opponent opens $3/$4 on a Tournament/Plan board with no trashing, that would suck.
Just buy Nomad Camp/Mountebank.
Better yet, buy Travelling Fair + Squire on turn 1. On turn 2, play Squire and gain Silver (optionally), buy Bonfire to trash Squire and Copper and gain Goons!
That's freaking OP!
Or, you know, just buy Goons on turn 1 using your Baker token.
Besides you can always buy Mission on T1, then Ferry onto Goons. On T2 you can then use your Baker coin and Borrow to turn all your Estates into *3* Goons via Inheritance =)
Of course the Minion and Margrave options are likely more overpowered still, but hey.
Had anyone ever bought Plan more than once in a turn?
Has anyone ever bought Plan more than once in a game? It just doesn't seem like something you'd do often.
Unless, you know, you didn't... plan.
Yep. Plan on Familiar, plan on village. If you have a steady stream of curses coming in then you very often want to swap from one massed card to another if you can. Familiar is one of those cards that you will buy a lot (particularly if you are not buying many other actions), but you reach a point where a spare $3 should move the token to some other card you intend to mass, e.g. Bazaar, Kc, Market. In a curse game you often want to trash at least 10 cards and you may want both the early trashing on an early card (like Familiar) and on a later card.
As far as more than once per turn, sure the obvious option is triggering on-trash stuff with emptying piles. E.g. Plan (move to Island), buy last Island, trash Hgrounds (gain EEE), plan (move to Nobles), buy last Nobles, trash Hgrounds (gain EEE). Game ends on Nobles, Islands, and Estates. On trash effects have many, many ways that allow you to edge case needing to spend $6 & 2 buys to trash two cards.