I suspect most editors and hiring managers are like me, which is why, unless you've been explicitly told not to follow up, it's always a good idea to check in. Use your judgement to gauge how many times and how frequently you can contact someone, but my general rule is a week after the previous email or phone call, up to two or three times. More than that and you have to be very tactful in order not to become a pest.
Corinna vanGerwen is a freelance editor and writer. She has worked as senior editor at Style at Home, senior design editor at Cottage Life and is the former Canadian Director of Ed2010. She has also held the position of operations manager at a boutique PR agency, where she handled strategic planning and daily operations.