whenever I want non-verbal communication w/others (who I C and dont C).
Standing ina lane, not till the light signals 'U may turn now" & I usually turn them off B4 the wheel duz so. Also 200 ft B4 the turn (law requirement).
On interstate when changing lane, but not as a request for anything. I change when safe to do so, signal 2, 3 sec B4, move there quickly, turn off signal.
But I'm pretty much the same w/hdlght use. Signal, expect action, too much delay I move on so as not to disrupt traffic. I often give 'left hand choice' (head-on or opposing traffic) as I'm no tailgater, but - if not taken I'll not wait, repeat the light flash offer, etc.