I know I've seen discussion about this before but I can't find any threads right now. On average, how many encounters does a hero need to face before he's ready to take on the next level encounter? ie: how many greens before he can take on a yellow? How many yellows before he can take a blue, etc?
When I say "ready" I mean how many before he can fight it with a reasonable degree of challenge but probably win? I know this will depend on how many XP it takes to buy an experience token, so let's assume a 4 player game. (4 xp each, right?)