Planets not only had to be defended from external attack, but occupied planets also need garrisons to keep the populace in line. Pau city is described as having every square meter under the guns of battle droids. (Revenge of the Sith novel) Gentres had ithe bulk of its population placed in a concentration camp and subsequently executed. (General Grievous) Such heavy defense was not limited to planets and cities – individual instillations were also well guarded. On Zaadja we see 26 formations that we later see are 24 by 19, plus an additional 19 MTTs defending a factory. This adds up to 13,984 troops. As there are still a large number of troops inside the complex, it is likely that an entire division of troops is defending the base. Lord Tyrannus’ private retreat on Ruhe (Clone Wars: When They Were Brothers) had a whole company devoted to it. Shu Mai’s private mansion on Felucia had an entire army dedicated to protecting it. (Evasive Action: Reversal of Fortune) A medical station on Boz Pity merited the protection of a squadron of ships (9 Resucants, 7 Munificents, 7 Providences, 7 Lucrehulks, 5 Diamonds), whose onboard droids would total at least 11.9 million droids without counting those carried by the Lucrehulk and Diamond class cruisers. (Clone Wars: When They Were Brothers) A small listening post on Praesitlyn was occupied by 1 million droids, with reinforcements on the way. (Jedi Trial)
The Republic could not easily bypass such fortifications – destroying the droid control computer would not shut down all the droids. The Confederacy has adopted a policy of dispatching multiple control computers to fronts (Hero of Cartao) and of programming each droid with general orders it would follow in the event that the control computer was destroyed. (Revenge of the Sith novel) The only way for the droids to be remotely deactivated would be to use the command codes possessed by the leaders of the Confederacy, which is what Lord Vader did (Revenge of the Sith novel)