I agree with the above statements, but in addition, missing a milestone is a bad thing no matter how you spin it. Take it as a learning experience for future improvement you may think, but in reality depending on how big the company is a missed milestone can be the difference between renewed funding and loss of contracts. Take a public biotech company for instance, the company will have shareholders and these people are in the know when it comes to when a milestone is supposed to be hit. If the company misses a major milestone its share price could sink incredibly low intra day when the news hits, thus bringing the value of the company down and may deter future funding opportunities especially if the next milestone is a ways away.