everybody's different. some will only smoke a pipe once a day, but have 3 pipes a day. if you only smoke that pipe once a week, that means 21 pipes in any given week (assuming you smoke that much).
I try to keep a rotation. I have 10 pipes. If a VA blend strikes me, I'll smoke it in one of my VA pipes. If I want latakia, one of my 2 lat pipes. I have 4 pipes for aromatic tobaccos. 2 for cavendish, 2 for others (altho I will bend the rules on occasion).
I think the biggest mistake I made first starting out was only having one pipe, smoking once or twice a day, almost everyday of the week. Unfortunately, it was my grandpa's old pipe, and now it doesn't smoke so well. I've done my best to clean it, but now I only break it out for special occasions/tobacco