I use a joystick mounted on bars, tilted slightly down to the ground on full as well as a road light on flash. The reasons for this are 3 fold.
1/ I commute along a two way cycle path for some of the commute which is on the pavement by the side of a busy road. The fact its by the road means that i also have cars coming towards me with headlights on which can make it difficult/impossible to see cyclists coming towards me with these “be seen” lights. Working on that basis anyone riding towards me would struggle to see me coming if i didn’t have a descent light on as well.
2/ Some of the cycle path is unlit so a good light is needed to light the way & see the dog walkers who don’t feel they need to be lit on a shared cycle path and quite often stand on one side of the path with the dog extension lead across the path while their mutts sniff along the otherside 8O
3/ I’d rather have a light brighter than i need than one where the “sorry mate i didn’t see you” arguement could be used. If they can see you they are less likely to hit you IMO.