Knowing When To Quit

Lately there has been focus on quitting,
quitting the big idea,
quitting quickly, etc.
so when do I know when to quit?  

Based on missed benchmarks. 

Over a year ago, I started up a new venture. 
I had benchmarks for testing and for implementation. 
Cost benchmarks
(I had a price ceiling so 
margins could only move so much),
time benchmarks (production)
and sales ramp up benchmarks
(in writing so I couldn’t fudge with them). 

The first two, the venture aced. 
The third?  It bombed. 
I tweaked.  Still bombed. 
I tweaked a few more times. Bombs away. 
So I folded and moved onto the next venture. 

Was it a difficult decision? 
Of course it was. 
But it had to be made.