A good plan lead to good start, a good start means half of success.
Where is the another half of success when launch the search engine campaign? It's depend on the good execution of the project. To control the search engine campaign well, the maintain and optimize operation are very important.
Every search engine campaign maybe had obstacles which can't be forecasted entirely. Because you're not playing the game alone, your competitors may increase the biding and ad position, may get higher quality score than you, and even revise their ad creative to attract visitors based on your concept.
Generally, the problems occur in these place, the CPC is high, the money spent too fast and the conversion rate is too low, and so on. We had to solve those problem as soon as possible because we won't let the money burning without return. A professional guy on search engine advertising must have following knowledge or skill to fight up with campaign issues.
It's not too easy to maintain and optimize the campaign, and any campaign can be run better performance than before, just optimization.