Just the free card at each is probably "enough" but 1 or 2 extras may save you more than 50 teeth of heal - and make sure you don't come up short.
You still have to beat him..
You get the boss' chest + cards. But then he still has them so you can beat him to take it again. So in the optimistic case of 4 thieves, you can take the boss rewards 5 times in one dungeon.
I just used all of my keys in one city, trying to get the daily special, and did not get it one single time.
Why?
The 4 extra cards should be enough if you are redrawing properly and using the appropriate level cards against the current enemies. Weaker cards first, mid cards second, strong cards last.
It's covered at 5:40 on the tutorial video.
Another thing Ms Fast Talker said, when you redraw, an ability card always shows up. So, 4 thief cards and it is the Boss, all can be played via redraw, worst case, for 5 teeth each. If you have other ability cards, they may show up instead of thief. This is where I like Soul Sever, some videos didn't like SS. If you have SS and it shows up instead of thief, play it, it takes the boss to 5 HP and I typically have a few cards left that can 1 hit kill AFTER I use all the thief cards. If you use Frenzy and it comes up before thief, there is a 33% chance to kill the boss so you would have to redraw to get all your thief card played first, then use frenzy last. It happened to me in beta when I wasn't paying attention and Boss got killed with 2 thief cards not played, unhappy is one way to describe it, there are other ways to describe it...lol
It depends on how many encounters are left! If you have 3 encounters left and 5 special cards with at least a heal card, maybe you only buy 1 more! Especially a steal or frenzy!
You need some bad specials in order to appreciate the good ones!
