The overwhelming number of projects fail to deliver. In my view, here are 5 common reasons why your projects are going over schedule, over budget, and generally under expectations of quality.
1. Overextending on your resources: Or simply doing more than what your resources whether it be in finances, human capital, strategic partnerships, time, etc.
2. Micromanaging: Instead of delegating and trusting that your team members. To me, this is huge.
3. Lack of strategic vision: You're being too tactical (putting out fires, playing catch-up vs how to sustain long term competitive advantage)
4. Eating an elephant whole: no matter how well thought out the project is, the individual pieces may be perfectly executed on time and on budget but then it's impossible or extremely difficult to integrate the pieces. Instead it is probably a better idea to chunk out the projecs to produce measurable results such as described in the "rapid results initiative" where specific quantifiable milestones are set, and once reached can be either built upon or scrapped depending the the goal discovery process.
5. Poor communication between cross-functions: Bureaucracy is part of the game, get used to it, or better yet, learn to be a better communicator and have not just let the marketing or engineering head decide on the project requirements but set aside time to get insight from all constituents and stakeholders.
Not only do failed projects cost time and money, sometimes amounting to several years, and millions of dollars. But it demoralizes all the stakeholders to the project, especially the frontline employees and managers that had direct reign and input into the project.
As has been quoted in the media and surveys, the majority of projects fail to meet expectations or even sustainable results. Therefore an improvement in the knowledge of the field of project management is perhaps the bare minimum in advancing one's career, or business success in this high paced environment.