You probably wouldn't need to do both Grammar 5 and Keys to Good Language 5, particularly if you are also using Language Arts F. The Grammar 5 has a very similar feel to our Language Arts Activity Sheets. For this reason I think that the Keys to Good Language would be a better fit for "drilling" if that's your primary goal. If you would prefer a more holistic approach that will work with your readers then the Grammar 5 will be better.
(Note: The same thing applies to Grammar 6 vs. KTGL 6.)