You will find that a few forum members don't even ride their e-mtb's in day time, so no hope of night riding.
The vast majority of my off road riding is carried out after daylight hours, and I'm usually out three to four evenings a week. Obviously the need for lights during summer use isn't quite so critical, but generally speaking, the lights stay fitted all year round.
The light of choice for me, is a Fenix BT20. The spread of the beam makes fastish off road night riding safer and easier when compared to the spot light effect of the cheapo cree lights, where the spot light effect of the beam works against you/me. The only downside of the Fenix as a standard, is that it only runs a two cell pack. I used to carry a second set of batteries, but have recently adapted things in order to run six or eight cell pack.
That's not to say that I don't use the cheap cree lights, and indeed I have two 1 Cree and one 4 cree lights. I tend to switch around depending upon where I am riding. I always keep a 1 cree in the Camelbak as a back up for the Fenix BT20.
With Cree lights for a full evening of riding, you really need at least a six cell 18650 battery pack, and not four.
A 1 Cree light is also useful when helmet mounted, but I don't ever mount anything to the helmet, as the risk of head/neck injury is too great. Much of my riding involves tight technical terrain, and as things stand, the helmet is also clouting low hanging branches. Even the Camebak often takes an unhealthy whack.
Cheap Cree lights aren't free of problems, but given the quantity produced and the price, you can't go wrong as a general purpose light. Problems include, water ingress behind the lens, mounting screws that work loose, tight or loose connectors, and the Velcro strap on the battery cover breaks off. But as said, given the price of the lights, these problems aren't a worry or concern.
I'm not worried about the quality of rear light for my riding, and just buy a box of cheap as chips lights direct from China using Ebay, and pretty much throw a light away after a few months of use. I've either lost or damaged too many rear lights, to want to spend out for one. I do keep a spare light in the rucksack as well though, which has now been used on two occasions.
The first two of the following clips are slightly unfair, as the red rear light of the bike in front is throwing the camera light sensor.
One cree. Wet ride, with short trip along a stream bed at 3.55 point.
Two single cree lights
Four Cree. Another wet ride. The beam is too focussed.
Four cree plus one Cree. Yet another wet ride.
I only have a crap clip of the Fenix in use, but here is the promo clip. The strobe mode is just plain dangerous to other road users. Also the beam is more yellow than bright white as shown. Not sure how they achieved that.
