I didn't write them down, but I get around ~300 credits per game I'd say and they barely last longer than 5 minutes. I play strike exclusively.
Here are my credit stats for 5 hours played, 20605 credits (now with redeemed challenges, which amounted to 4450).
So, again around 3k credits per hour without challenges. Which is also roughly in line with my previous 13k credits at 4 hour, including the few credits gotten from daily login chests. If a strike game on averages takes like 5 minutes, that's 12 game á la 300 credits an hour, which would be 3600 credits an hour. Obviously, some games take a bit longer, so I'd say 3000 credits an hour is definitely normal and doable.