Missing milestones is not so bad if you either have the foresight to anticipate issues or if you have well-developed contingency plans. Missing milestones become an issue when something unexpected happens that you weren’t prepared for. For example, say you’re building a device that is supposed to interface with an ECG, and you procure parts for the device. Something like faulty components from third-parties could really cause you to miss milestones. But faulty components isn’t something you expected since you placed trust in the chip manufacturer to deliver quality products. Missing milestones don’t always hurt projects, but missing a significant amount will drive the budget of the project up and cause significant delays for deadlines. This could be detrimental for patent applications, subsequent milestone deadlines, and can hurt commercial viability if the device comes out at an in-oppurtune time, i.e., a competitor has already made it to market before you. Being able to adapt to missed milestones can lead to overall success in the long run because it provides experience for the entire project team and enables them to develop foresight on potential issues in subsequent projects. There are pros and cons regarding the effects of missing milestones, but as a whole, the project team should do its best to avoid missing milestones.