a.) If adding leafs is has net gains, the tree will do this even if it's not the most efficient way (where say it could only have 50% of the leafs). b.) A tree

a.) If adding leafs is has net gains, the tree will do this even if it's not the most efficient way (where say it could only have 50% of the leafs). b.) A tree is fighting with it's environment for light and space, a linear setup of leaves might not be the best position to fight other plants for light. c.) A tree needs to support all leafs with water, nutrients etc. A tree layout might be more efficient