This question contains movie plot spoilers.
So in the film Star Trek (2009), Spock wastes about 10 precious seconds explaining to Uhura why he needs to beam down. As Captain though, he shouldn't need to explain his actions, especially in the middle of a crisis. When Uhura said "Spock, wait! Where are you going?," he could have simply said "No time to explain!" and then only after he beamed back up explained the significance of the Katric Ark and the necessity of beaming down in person. Most importantly, his mother was lost when the rock ledge collapsed about 12 seconds before completing the teleport, and Chekov declared her signal as lost only about 9 seconds before the teleport was completed. It appears that if Spock hadn't taken the time to explain to his Lieutenant, there is a chance his mother could have survived by him arriving on Vulcan 10 seconds sooner. Even in a romantic relationship with Uhura, it does not seem Logical for Spock to pander to human emotions in such a situation, so why does he pause and take the time to explain to her what his plans are?