ps: if no one is using a secondary, where do you age beer. you do not want to leave on the yeast cake forever? wont dead yeast cells affect the product after time?
If I'm doing a normal beer (e.g. not sour or something meant for aging), I usually do a 3-4 week primary. If I am doing say, a Belgian Golden Strong, I primary it for a month - by then it has dropped clear on its own - take a gravity reading/taste test then secondary for 2-3 months. I can rush this process along for smaller beers, but it's all done by feel. There is no set timetable for the fermentation in my brewery, it is all done by sight (gravity readings), taste and smell.