When it comes to lithium-ion batteries however, nothing could actually be further from the truth. Lithium-ion batteries are typically found in most portable electronics such as smartphones, the Oculus Quest, and most electric cars.
Apple recommends, as do many others, that you try to keep an iPhone battery between 40 and 80 percent charged.
I would say more moderately that the sweet spot is around 50% charge, but you should try to stay between 20 - 85% charge with your Oculus Quest (or phone) and NEVER go below 10%.
Any battery usage below 10% will impact the total lifespan of your device, and I would highly recommend only doing this for emergencies. If possible, turn off the device and charge it up to between 50-60%.
The reason for this is fairly technical and is related to the battery chemistry. If you want some more detailed information click on this link