Well having been inspired by the wise ones here, I decided it was not prudent to smoke any particular pipe more than once a day and thereafter to provide it with a full week's rest after its ordeal (the 7 day rest period being my justification expansion on their "couple or few days" rest routine).
On that basis, after doing the math, it would appear that I require a minimum of no less than 35 pipes for my rotation, and I'm working on it! I use this explanation to friends and family who cannot understand that one pipe is not sufficient, two pipes is an overkill, and, three, well that's just sheer gluttony and madness. It has been stated that any more than three is "fit for committal to an asylum, so if I take a holiday you'll know where I've gone! Wonders if it still requires 3 x signatures to summons the men in white coats bearing straight-jackets?