I've been testing 2 campaigns for 2 weeks, I broke even, but didn't profit. This time I tested them more or less properly: I compared this week's data to the previous one (earlier I just did Tuesday vs Monday, Wednesday vs Tuesday, etc.). I had more conversions on Thursday and Friday, but I have no idea why. Probably by the end of the week people thought that it was about time they solved some of their problems.
I was also split-testing two ads per ad group from the very beginning: if the commercial intent of the KW was pretty low, then no matter how enticing the ad copy was, clicks and conversions were low or non-existent. Though this time I had fewer KWs that would attract people in the "browser" mode. On the other hand, even if the KWs seemed to be of high commercial intent level, CR would sometimes be low.
So.. you already know what to do to get it profitable:
I had more conversions on Thursday and Friday, but I have no idea why
So, don't run the campaign on any other day.. maybe add the third largest day for kicks.
Then kill the worst performing ad group.
The split test some more.
::emp::