Horizontal or vertical light?
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Because if light doesn't reach part of the canopy, it does not develop and eventually dies off.
Try growing some plants, and you will see what I mean. If you veg a plant too big for your flowering light, you have just wasted time and energy. There is an optimal point for any given flowering light intensity over any given footprint for any particular strain for any particular style of grow that will produce a given yield. It is up to you, as the grower, to discover what that optimal point is depending on your system.
That is if you wish to grow efficiently and are not just vegging to fill in time in-between flowering cycles.