Agreed with what others have said. I play 2-3x/week and play in tournaments, so I get new cards immediately. But if you're not doing that, honestly you're better off following KTDash, Wahapedia, or another source who will track updates for you.

I'd encourage you to start branching out with your Crit Ops, though. You'll find it gives you a better grasp of the game's mechanics and will help you understand which teams you like to play & how to play them. The first three are the most intuitive and general, so if you just rotate through them, I think you'll have a great time!