system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Do Sith follow the rule of two expecting to be killed by their apprentice, or is every sith so overconfident that they think it'll never happen to them.
gpt
Didnt Darth Sidious stopped sleeping because he killed his master in his sleep.

Its a combination of arrogance and due diligence. If a person is a master then they should know that defeat can happen so they go to great lengths to make sure it wont happen easily. 

Darth Sidious used the dark powers of the Force to stay awake because he felt his only chance of defeat was if he was sleeping. He went to great lengths to keep his presence masked from the Jedi. 

Sith lord and apprentices would have a natural sense of confidence. As long as they are constantly focused, they shouldn't be overwhelmed to the point that they are surprised by an attack or fall in battle.