The importance is that by and large, 2 drugs are recommended for
patients who are deemed well enough to aim
for extending survival. You asked in the other post about the chances of making it til June, if she is receiving only 1 drug, and is pretty much in bed more than half of her waking hours - the goal of treatment may be to improve symptom control - not really halting cancer progression. If this is the case, her chances would be less.
Stay positive.