The first question you must do is how fast do you ride at night? The faster you ride, the more lights you need. Making the math, when you ride at 60mph (100km/h) in 3 seconds you advance 250 feet (84 meters)!!!! Thats a lot!!! Now, 3 second is the time you take to touch the brake reduce speed and maneuver. But let's make up the scenario… You plan with your buddies an adventure day, probably a trail riding with some single tracks… you're expecting the ride take all day long and return home before sunset.
But on The trail the group got lost, some flat tires, maybe a mechanical issue, or the bikes had to be push/lifted over a hard pass. You're exhausted!!! Your reflexes aren't the same and it´s dark, damn dark.
Now my question is: Would you leave the stock light knowing it roughly lightens 100 feet (30 meters)? 100 feet you travel that distance in less than one and a half second and still you haven't seen the cliff ahead!!!
Think about it,