My first week playing Halo 4, I hit the xp cap every day. I believe it is around 160,000 xp a day, which includes xp from challenges, commendations, etc. Now every day I hit the xp cap it took me about 8-10 hours of playing war games (using double xp). You get anywhere from 4,400 to 5,900 xp a match using double xp.
In Spartan Ops online you can hit the cap in about 3-4 hours, each game using double xp you get 11,900 xp (not including any challenges or commendations you may have completed)
Now if you spend all of your time in Spartan Ops online, you are going to hit the cap very quickly with or without double xp.
I don't like the xp cap either but they were smart about it, 8-10 hours in war games with double xp, now take the double xp away and that is 16-20 hours to hit the xp cap. I have yet to hit the cap without using double xp and to answer a earlier question, when you hit the xp cap, you earn no xp, from challenges, commendations, etc. So my advice when you hit the cap, either go play campaign or forge or custom games or play a different game because if you complete a commendation after you hit the cap, you will lose all of the xp from it.
I hope this helped to clear some questions up
Also I am SR 73 so even with the cap in place it is still possible to get to a high rank pretty fast.
