Well most of the time plants dont become N deficient untill well into flower.If your nute mix is right then it's prolly not gonna be N def. In late flower if a plant becomes def. it's usually not a prob.
However over-watering is often miss-diagnosed as N def. becouse root rot caused by overwatering will look like several deficiency...becouse it is.It means the root's wont absorb nute's correctly/sufficiently.