For most users a simple lanyard is fine...like you'd use for a camera.
I would NOT recommend a bungee cord, as if you were in the type of situation where you did drop it, it would then bounce back and whack you, and/or whack into other stuff....and on a ladder, deck of a boat, precipice, etc, that can get messy. A simple cord/non-stretchy lanyard so it would drop and just dangle is preferable.
When I think of it, I tend to use a simple version with it looped loosely on my wrist...if I WANTED to drop it/let it go, I just "point at the light" w/o my wrist bent, etc...and it can slip off.
More often than not, I just use the glow in the dark lanyards to see where the light is, but don't actually use the lanyard to secure the light...because for work I swap lights so frequently that its too much trouble.
The down side of that is that I DO drop lights, all the time. I've even had holsters rip and the lights tumble out, etc.
The upside to the down side is that I do tend to see which lights can SURVIVE being dropped.
The LAST one I dropped bad that way was a TN30 that the holster ripped while I was climbing....and it bounced off some stuff than free fell ~ 6' or so IIRC, and whacked solidly into concrete. It still works, but does have a little dent in the bezel where it landed....and some dirt that doesn't seem to want to get out of the knurling from the sludge it then skittered into after the fall, etc.
If I'd had a lanyard or keeper cord for it ATTACHED to something (Me for example), it would not have got slammed up so much, but, most of the new lights are pretty tough so far at least.
So, I mostly worry about LOSING a light more than it breaking.
If around the kind or machinery that can suck in loose clothing, hair, cords, lights, appendages, etc...yeah, no freakin WAY you want ANYTHING that will pull you in.
The force to break the lanyard, even a fused one designed to break away, might be too much to prevent you from not having a hand guided into the pinch point, etc. Those things tend to happen very quickly.
Most of the break-away type fuses are more so you're not strangled as far as calibration forces.