Suppose my five level-2 player characters (PCs) face 10 CR2 challenges/encounters in a given Pathfinder session. To be concrete, let's assume these encounters are monsters that are each worth 500 XP. I could send these monsters at the party individually or en masse....
Case 1: Individual Encounters
The PCs face each of these monsters in separate encounters separated by a significant amount of time (>20 minutes each). Each encounter is relatively easy on its own because the five PCs can easily gang up on a single monster, so the PCs defeat each monster with ease.
Case 2: A Single Massive Encounter
The PCs face all of these monsters at the same time. They are severely tested and nearly die, but they manage to survive.
If the party defeats 10 monsters worth 500 XP each, the party would earn a total of 5000 XP, or 1000 XP/PC. In Case 1, they expend little effort/resources to do so. In Case 2, they use much more resources and the whole encounter is far more difficult. It would seem that they should earn more XP for Case 2 than in Case 1. (Then again, perhaps the PCs were clever and somehow planned to face the monsters individually, so perhaps their planning should be rewarded with easy XP.)
Are there any rules/suggestions in core Pathfinder which help account for this? For example, in 5e, there are evidently "Encounter XP Multipliers" when the party encounters a bunch of monsters in a group which change the "effective CR" of an encounter (c.f. this question). I seem to vaguely remember 3.5e having something similar, where the "effective CR" would be different. Does Pathfinder has a way to do this?
Disclaimer: I acknowledge that GMs award XP in different ways. Some would add up the XP from each encounter/monster, some would calculate XP based on an "effective CR", others might award XP based on their own estimate of the difficulty, and still others have their own approach. I'm looking for core rules (preferably) or published 3rd party rules.
This situation happened a day or two before I posted this question. My players entered a spider-lair cave with spiders, bat swarms, pit traps (with bodies and minor loot), cave fishers, and similar challenges. They had something like 8-10 such encounters, plus a few others I'm not counting. They used a torch to light the spider web on fire, which spread throughout the cave, dissipated the bats, killed several spiders deeper in the cave, and so on. The pits were not deadly (though they hurt), and after the second one, they decided to creep through the cave very carefully, specifically looking for pits to avoid. When they found one, they hopped into it looking for loot. Thus they "defeated" a half-dozen pit traps -- as well as the spiders and bats -- super-effectively. They earned more XP in this session (calculated normally) than they had in the three prior sessions combined. I felt really bad giving them so much XP because one of the PCs was absent (house rule: absent players don't get XP for sessions they miss).