Hi Savage,
There is some reallly good info in the blogs I link to here.
Power of Discipline plus Hidden Dangers of Constant Stat Checking
http://affiliate-blogs.5staraffiliat...stat-checking/
Not sure if it will give you the exact answer but I remember one of his articles talks about getting too nervous and pulling the plug on KW too fast. If I remember right both articles have some really good PPC advice.
I don't do PPC as an affiliate, just to drive traffic here to 5 Star which is a totally different animal.
I would think to some degree the answer depends on the product or market you are targeting. IF its a freebie offer or a lead based offer where no purchase is required conversion rates could be higher. But on regular retail products the average conversion rate is only around 2%.
In addition to how well the merchant converts, your ad copy, pre sell on your landing page design or direct linking to the merhant all would play a part.