There is no simple answer to this question as it depends on many factors.
In general, the more light you can give a plant, the better it will grow. This is especially true for cannabis. However, below are a few factors that can affect your success and yield.
The wattage of your LED bulb
Different LED bulbs have different wattages. A 100w LED light will produce far more light than a 3w LED light and you should expect a much larger yield from that 100w light.
Avid uses a 300W light to provide your plant with as much light as it could need with an optimized spectrum to increase growth and yields.
The height and diameter of your plant
A large cannabis plant will need more light than a small one because it needs to support more leaves, flowers and branches. Just remember that if you’re growing an auto-flowering strain, you won’t see much change in size after 18 days (3 weeks). If you are growing regular cannabis seeds or clones then at least 2 or 3 weeks of vegetative growth is recommended before the flowering stage begins. At the flowering stage, you need up to 12 hours of lights on per day. However this also depends on your available space and how big you want to let your plant get. Overall, cannabis plants can double or even triple in size once flipped into flowering.
Distance from top of plant to light
If you want your cannabis production to be maximized then keep your light as close as possible without burning the leaves/flowers/buds. For that reason we recommend that you keep most LEDs 12 inches away (though certain brands may require less distance). Remember that the closer you get to any type of lamp when growing cannabis, the faster it will dry out your air. Make sure there is enough humidity around your plants if using HID lighting or anything else hotter than LEDs (such HPS/MH)!