Some, including myself, think, or hope, putting on reflective stickers on the back of the gloves helps when making turn signals at night. I think it's useful in only very limited situations, when the car light is directed at your hand, which often is not the case.
Any drivers here could provide some input? Have you been able to tell a cyclist's turn intention thanks to the reflections from their glove at night?
Depends on the application, I'd guess. For example, if you were turning on a highway you would not be visible until you were in the car's headlights (i.e. 200-300') or about 2-4 seconds at highway speeds. That would be inadequate warning in my opinion.
J.