I was going to put this in the check-up thread but it kind of grew. I hope it's okay here.

Theoretical question:
--early stages of a large MTT 300/600/100
--55bb eff
--fold to btn who pfr's to 2.83bb, he seems standard, neither active nor inactive, nothing went to showdown, 30's white guy in casual dress, lean and fit.
--sb folds so it's h2h
--bb is getting 3.18:1

I guess bb should call or raise with 56o and 57s but I know nothing about tourney's so please advise and give more of a range of what hands are close between call/raise and fold.

My concern is, from btn's perspective, I want to bet an amount that allows my opponent to make the most and the largest error's possible, and I think(tho maybe I'm drastically misjudging) giving him this price fails to do that with my btn opening range. I would say this is a fine open size if btn had 24o but not if he had 89s. Am I thinking about it wrong?

Are most people in bb calling w K6o getting 3.18:1 but folding if they only get 2.5:1(assuming bb is a modern and educated player)?

If you want to get all technical about it then you have to factor in the negative implied odds of playing useless trash hands out of position. The math may say you are getting the right price to call your K6 right now, but in the long run you`re not.

You should defend your blind with trash now and then just for the sake of defending it, but in tournaments if you make a habit of it you will cost yourself.

Of course I`m not exactly a modern player. I`m a guy in his 50`s whose been playing poker regularly for about 40 years.

They tell me the game has changed, but I still see the same things happening over and over.

I would consider defending with suited connectors, some one-gappers, off suit Broadways, sometimes hands like Q9 or J9. I would rarely defend with a hand that did not have at least some straight or flush possibility. I don`t much like hands such as Q7ss or K3ss. I am never defending with K6o unless I feel like somebody is attacking my blind too much. In that case I would be much more likely to 3-bet than I would be to flat and see a flop.

I just filtered for K6o vs open my heads up database. Over 316 hands in which I called a raise vs BTN (ldo), I lost 229bb. Meaning I lost less than I would have by folding, so call is better. I'm too much of a noob to filter for what raise size I encountered, but the sample would get smaller. There is no ante involved, so my equity to call would likely be somewhere between 25% and 33% based on the more commonly occurring raise sizes I'd have encountered.

I'm gonna go ahead and say, don't fold your Kx in the BB and certainly not vs BTN opens.

In regards to the other hands you mentioned, I'd say it really depends. What hands you choose to select as your 3bet bluffs depends on what price you get. The price determines which hands can profitably continue, and the hands which can't continue by calling are the ones you elect to 3bet as a bluff. So basically, a hand I might choose to flat vs a min raise, might become a 3bet bluff if they 2.5x pre flop.