Charts are ever-changing and their patterns are sometimes well-respected by historical peaks and valleys, support and resistances, and so on. Zones are often referenced for those types of occasions like supply and demand zones. For the day-traders and swing traders out there, charts often require smaller time-frame analysis to capture patterns that form within a day or week's time. I tend to refer to the 4 hour, 1 hour, and 15-minute time-frames in that order to create mark-ups like these to allow my trades to be more calculated.