I had take a moment to reflect upon your original post, your reply to me, & the general feel of your post.
Theoretically, you succeed to capitalize the full 5% cash back within the 1st year yielding you $300 back from spending $6000. You put down $5K making your total $5.3K. To achieve this goal, you'll need to spend 6K within 3 months & get your cash back before continuing with your plan This translates into you spending $6K before spending another 5K. Also, 5K at 1% back is $50.
8% of 5, 350 is $428. Discover gives you $350 at the end of the 1st year. You'll get $1,128. Alright. It sounds like a solid plan.
Yup, a solid plan under ideal conditions.
The problem you are clearly fail to realize is the world is not ideal. Honestly, the closest ideal plan world has come up in recent years was the Paris Accords agreement. Boy...we sure did fucked that plan before it had a chance to function.
I'll leave you with a quote from my math grad professor, "Only foolish people execute ideal plans. They end up failing before they can reach it. Be wise but don't believe idealism bullshit."