It depends on how aggressive I'm riding and the flow of traffic. I try to not blind people unnecessarily, but if there's enough of a cluster of cars, on for sure. On streets where there could be an oncoming car making a left, and spotty traffic going the same direction as me, OFF so that it's not harder for them to gauge distance and speed.
I never ride in the middle of a lane and in heavy traffic 'wiggle' so that my headlights will make me more likely visible in rear view mirrors. I also never ride perfectly straight. I alternate between left and right side of a lane, to keep jackoffs from deciding to merge next to me and expecting me to read their mind when they're in my blindspot. I think that's more significant than high beams on/off.