Simple one - in the composition settings window you can use maths funtions in the Width and Height fields to quickly scale the comp dimensions (e.g. *2 to double), and it works in the frame rate field as well.
It would be a really nice QoL update to be able to do the same in the comp Start Frame and Duration fields.
A use case example would be retiming an animation to fit voiceover changes - knowing that the comp needs to be extended by say 75 frames and being able to type in +75 to duration would save a little bit of time, which adds up over the course of a project.