I came across an excellent post today that analyzes the “how do you know when to quit” question from the lean perspective.
I found myself nodding in complete agreement to this especially:
"If your acquisition efforts are failing, there need to be signs from other places in the model (conversion, upsell, retention) that the business is on the right path. If you’ve been at it for a long time and acquisition is poor and everything else is muddling along, then it’s time to quit. However, if you have found that you can either convert, upsell or retain customers well, then keep plugging away. The feedback from users is that your startup is on the right path…. now it’s time for incremental improvements in the other areas of the model to allow the business to reach the next level.
The original post is here.