That goes along with the saying...too much of anything is a bad thing. Its assumed. For our setups, the minor camber most of us encounter isnt a ridiculous amount. I would say a few weeks to settle is also a very liberal amount....maybe a day or two. I wouldnt drive around on an unaligned lowered car for long...if the camber is extreme enough, you'll end up like the guy above who went through his tires in 1500 miles.

The key is to monitor your own wear. No two cars are the same, you cant follow any general rule, be it a 2" drop, -2.5deg camber...you can only use them as a guideline, not as a rule. Pay attention to your own setup, and determine yourself whether or not you need a kit.