I just finished the event this afternoon. I didn't use any donuts to speed things up, didn't spend donuts on cheater or banners or walls, didn't speed up tasks. I have not changed tactics since I started, unless you count tapping buildings but that's beside the point.
Reality is I have played every 2 hours to get nerds, sent them on attacks, tapped on shields to clear them. I am probably not too popular with neighbors since my town is pretty high(level 16 castles) but then again most of them are also the same level or higher.
Bottom line: EA didn't do this to make a huge amount of money. Look at the timing: I believe it's meant to get people into the game more than anything. Start of a new school year for the vast majority of the USA, with colleges in session starting in the morning- it's a perfect time to get them into the game!
