I use my turn signals when I want to communicate with other drivers
Would you ever not want to communicate your intentions to another driver?
As I often have to remind my students (I teach a 12-week Cooperative Group Cycling Skills class every year), signals are a form of communication
...which means the communicator must convey information to the communicatee or else no communication actually took place. If nobody sees your turn signal -- because it wasn't engaged (sic) long enough, because it wasn't explicitly clear, because you neglected to use it...or because they weren't paying attention -- it doesn't really matter that you signaled; you failed to communicate. If a tree falls in the forest yadda-yadda-yadda...
But more importantly, I remind them that signals are to communicate what you intend to do, not what you are currently doing. They need to be used with foresight, in advance of any action. Way too many drivers don't seem to have received that memo.
I feel that driving licenses shouldn't be renewable online like they are now unless it's due to a change of address or name change. I would rather have everyone retake the driving test every few years.
Oh god, yes, please, ^^^THIS! A million times, ^^^THIS!!!