The aim is to be accurate with film exposure and development, knowing that there is some exposure latitude to compensate for error and variation. You can get away with underdevelopment far more easily than with overdevelopment, and you can get away with extreme overexposure better than with slight underexposure. Print quality actually improves with modest film overexposure but is very sensitive to underexposure.
Overdeveloped negatives will not print easily, but minute underdevelopment is easily corrected with a harder grade of paper. Film exposure latitude is what you can get away with, but when in doubt, overexpose and underdevelop.