You can take a pen and a pare and make a road map. But implementing that plan is the essence. The pen will write as you like. But human beings will not be like that. They will have their own brains and making them follow the exact instructions is a herculean task. He will never do want you to want. He will definitely add his own thoughts and the problems will start there.
Many projects fail in implementation only. I have been observing this in many projects. The delay is mainly due to human mistakes and laziness. Another issue is that in planning many will never consider the difficulties that come in execution.
Probability a theory based on Assumptions and Negativity(Elimination). It is used in the evolution of atomic theory.--- Bhushan
"Life is easier when you enjoy what you do"
Knowledge is power.
It is only with a plan and target and deadline that we can know how it is progressing. By review in that we can do the necessary changes to complete the proper implementation even with some delay.
In the related case of cleaning the drains, there is no use cleaning the drain s too early. As most of the public drains are open drains partially or fully solid waste get into it continuously, many times being deliberately dumped by people. So the cleaning can be most effective only when they are cleaned just before the rains start.
For spending public money there are many procedural stages due to which the actual implementation also gets delayed. The funds are allotted in the annual budgeted and the local body's financial position and availability also effects these works. Of course for any problem there can be proper solutions only if sincerely attempted.