He's a little tip that helps me a lot in dungeons:

If you ever get split apart from your partner (Example: Stepping on a Warp Trap.), you can find him/her/it, or you can hope your partner can hold itself up for a while! If your partner is especially strong, ditch him/her/WHATEVER for a while. After your partner walks around, check it's stats. Since the camera goes over your partner, the current area it's in will be luminated as if you explored it! This is helpful if you want to cover more ground and find the stairs faster! Try it! Once you get the hang of it, this might become one of your casual stategies!