I can't stand the feeling of jeans that have been sweated in. For me, no level of sick fadezzz is worth wearing summer-sticky denim. Machine wash, line dry, no stankiness, no worries. And though I can't speak from experience, as I seem to destroy jeans with impunity, jeans will probably last longer if they're frequently washed.
Washing jeans actually does increase longevity, as dirt and sweat break down cotton fibers.
Personally I only work on my "fadezzz" jeans during the cooler months. Works pretty well for me