I'm taking my first B&W photo class in almost 20 years, and printing for the first time in that long as well. We're printing using Ilford Multigrade IV RC paper, Ilford filters. I'm trying to develop a feel for when to change contrast grades and when to adjust exposure time to get the look I want in a print. There have been times when I thought "I need more contrast" but simply exposing the print for longer gave it the look I needed. My question is: are there any guidelines on when to adjust printing time and when to adjust contrast grades? I tried asking my instructor, but she told me that she "had to re-learn B&W to teach this class and is not a good person to ask that kind of printing question."