Plans by themselves do not guarantee success. They need to be backed by focused effort. Even big organizations are not immune from problems and failures in the implementation of their plans. It often results in huge financial losses and loss of markets. According to one estimate, more than half of the projects initiated fail due to improper planning and execution. Plans fail for many reasons. Some of them are listed below.
There are quite a few other reasons why the best laid plans fail. However there are two reasons why they fail most frequently. One is the lack of discipline. Working towards a target require step by step trying and adherence to the plan on your way forward. However irresponsible behaviour and lack of ownership to the task in hand, is a definite way to failure.
The next is the lack of confidence in the plan. This is especially true for group tasks. The time to understand and express lack of trust in the modus operandi of a project is at the time the plan is made. One set afoot, there is no room for lack of belief and such disbelief can only lead to the failure of the entire program.
Plans are made to succeed. Their success depends on the wholehearted and disciplined effort. Yet there is always the possibility of failure. Failure of a plan is no reason for giving up an objective or cause. And the most important part of planning is to ensure that the time spent is worth the objective to be achieved.