Halo 4’s released with a daily XP cap, meaning you can only earn a set amount of XP in a single day when you play the multiplayer. Though the exact number isn’t specified, it’s probably around 75,000.
Why is this the case? 343 explains.
“The daily XP cap is intended to preserve the integrity of the progression system,” Jessica Shea, community manager, explained on Halo Waypoint. “In other words, it’s in place to provide an early gate from players running amok in their progression. When we launched, we had a bug where double XP tokens were being consumed even when you went over the cap. That has since been fixed. In the coming weeks, we will be monitoring how many players are hitting the cap so we can respond accordingly.”
Halo 4 released a few days ago for the Xbox 360.