Not to say I can't use them up -- I regularly run pens dry -- after many years of using them.
I was gifted with a bar of soap for xmas 2007. I resolved that I wanted to use it, but that I needed to use up the prior bar first. I'm using 4 different soaps at the upstairs bathroom sink now -- a liquid citrus anti-bacterial, a liquid moisturizing, the liquid that came with our water softening system, and a bar. I use them in reverse order, and every day I start over -- so every day that I am home and use the sink, I will use the bar. If I use it a second time, I will also use the "Rainsoft" soap...
This is not even getting into to two nearly full gallon jugs of soft-soap that I bought at Pace.
The bar was a disc that might have come from a hotel. I think it was less than 2 inches in diameter, and less than half an inch in thickness. At the end of February 2009 (after being used roughly every day for 14 months) it broke into two half-moons... which are still hanging on.
2 or 3 weeks ago, the hotel soap that a friend used and decided she didn't like and gave to me -- that I use whenever I travel -- finally was used up. I think it started that weekend larger than the aforementioned soap, but perhaps the water where I stayed was very "hard" and the soap just dissolved.
I think of this now because I just had to throw away a Dish-washing liquid container -- there was no recycle marking on it.