$8,400 over three years is about $230/month. And aside from the opportunity cost of your labor to optimize that, you should also theoretically account for any purchases that you wouldn't have made if you weren't trying to optimize your points (if any; I'm sure it's hard to attribute).

With current interest rates of around 5%, one could get the same stream of income ($2.8k/y) by just plonking $50k or so into a high-yield savings account or money market fund.