I run two tactical flashlights -- on on my bars and one on my helmet (plus I carry a 'reserve' light in the panniers). I also run a flashing red light on the back of my helmet, a steady red light on the back of my rack, and one more blinky on the back of my panniers (with red reserve in the panniers, as well).

In full daylight, I generally don't bother much with lights, because in my opinion, they really add very little as compared to high vis clothing (I wear a reflective, hi-vis orange vest or hi vis t-shirts in summer, and a hi vis jacket w/ reflective accents in winter). I base this on what I see as a fellow cyclist approaching, as well as my experience as a driver coming up on cyclists.

I do run some or all lights during any periods of diminished light (fog, dawn/dusk, clouds, or when I know I'll be passing through tunnels or underpasses, or even streets that are particularly tree lined).

As a cheap solution for the front that is better than the typical walmart/target offerings, I would advocate for the tactical flashlights available from Costco (if you're a member) -- its a 3 pack of nominal 150 lumen lights for like $15. These are bright enough to 'see' by if you keep your speeds really modest, though you won't get the kind of road detail you really need for traversing unknown or serious dark streets. I use them on some unlighted stretches of MUP with reasonable comfort at speeds near 10MPH. One nice thing about mounting one to the helmet is that you can point the hot spot where you need it. They also have a pretty good flash mode for the 'to be seen' aspect. Not a perfect solution, but better than most offerings near the price. NOTE: These are NOT the tactical flashlights offered on Costco.com for a lot more money. I have not tried those.