Poker is such a situational game, depending on the opponent, an easy fold can turn into an easy 3 bet. There is no stardard line in any situation becuz so many different varaibles govern every hand.

However when you have no read on your opponent, there is a standard line to guide you for many situations in Poker. When you have a pocket pair, and a higher card is on the board, and an unknown checkraises you on the turn, you should fold. With no information, folding is the prudent move.