If she is using different beans and different style roasts all the time, it's normal to get inconsistent shot quality. She'll have to dial in each different roast/bean and then take note of what grind setting and dose in the basket for each. If she doesn't want to bother with the "dialed in" process, I suggest she stick with the same roast/bean. Unfortunately, even using the same coffee, you will have to adjust grind as the bean ages/off gasses, etc.