I've been playing a lot of Torchlight 2 recently, which always has its dangers. For one thing, these ARPGs are so moreish that you can sort of chug through them forever while the rest of the world withers around you. But there's another danger, too. If I play any ARPG for too long in one go I start to think purely in terms of the trade-offs. It's sort of RPG thermodynamics, I guess. I cease to see health potions as little bottles of liquid that will help me out on my heroic journey. I start to think of them as a way of trading money and time for experience.
So I stock up and go, well, this will see me through a few floors, which means a level and a half if I kill absolutely everything. That's 2000 gold in potions, 10 minutes of grind, for two levels.
The game sort of falls apart at this stage. Worse still, this thermodynamic thinking, this heat-exchange approach to games, can transfer from ARPGs. The morning fossil walk in Animal Crossing becomes five minutes of wandering for 15k or so, because inevitably Blathers will have everything by now. I might start to ponder the value of helping Gulliver or Wisp. This way leads to misery.