Deciding on ways to monitor long term projects depends on the project. If the project is something that is visible, you can appoint a team to examine the product and report on its growth. If the project is something that is abstract as in a research project that involves reports of progress, then you can appoint a single agent to collect reports periodically, assess their merits and report to the agency that is funding the project. Self-monitoring of any long term projects are realistically possible with the monitoring left to the individual who is being paid to conduct the project. If his monitoring has been inaccurate, his funding is usually not continued at the end of the specified period when his results have to be shown. Many long term research projects conducted by individual researchers have a specified period of completion. To extend their funding, they must show results or make an explanation for the need of an extension.
Monitoring long term projects should involve the use of a monitor who is familiar with the work being watched. If the monitor is not familiar with the work or the research being conducted, his efforts are usually not predictable for the over all success of the long term project even at conclusion.