What is the disadvantage of using work breakdown structure?

Until you have a solid understanding of the work to be done, you can't schedule it, you can't staff it, and you can't cost it. The larger the project, the more deliverables, and the more steps required to produce them (unless you're talking about The Great Wall of China, which was more about repeating a relatively small number of steps for several dozen generations). Consequently, the more complex WBS adds even more significant value, in that it provides opportunities to seek out economies of scale (TGWoC), or alternative approaches (buy, lease, outsource) for some deliverables to simplify management of the project. for more you can visit www.ysapak.com www.fysisoft.org, www.madina786.com and www.siasat.info

A good WBS just puts all the cards on the table.