As mentioned above, you can, up to a point. Chase Freedom (a different card than Freedom Unlimited) has rotating 5x UR categories (changes each quarter), and from time to time (about once a year?) it may have groceries at 5x UR for one calendar quarter, up to a cap (which I think is $2500).

There are about 13 weeks in a quarter; $300 x 13 / 2 ($300 every 2 weeks for 13 weeks) would be $1900, so you wouldn't cap out the spend in a quarter based on what you said you spend. And thus you'd earn 5x UR for one quarter of each year. That may not be perfect, but isn't it worth doing for that one quarter a year? (And you may find other quarters' 5x promos worth it to some degree too, even if perhaps not as much as a grocery quarter.)