Metaphor extreme stress test

We're all familiar with the melting pot vs. tossed salad metaphor for multicultural integration. In the melting pot, heat is applied forcing everything to melt together into a pile of homogenous brown mush. In the tossed salad, everything is left to its own devices and allowed to retain its unique characteristics, thus contributing to a yummier and more interesting whole.

I just realized this metaphor stands up to extreme stress, because:

If you leave a tossed salad alone for long enough, it will eventually turn into a pile of homogenous brown mush! But it won't be very yummy then, so you have to keep adding fresh ingredients.