If you ask a scientific mind this question they'll tell you, without actually telling you usually, that nature gets it right every time, and nature knows better than we do. they're half right. we are nature. nature is doing the exact same thing we are doing. pushing every edge of every envelope trying to learn and grow faster, and faster, and faster. we're all, every living organism, trying to get through a maze as quickly and efficiently as possible. ITELLIGENT people understand that we don't even know what we're racing through the maze after. there's no metaphorical cheese......except for personal happiness. this is probably one of the main stemming reasons that the rest of the slightly-uncivilized world loathes the united states' unrelentless striving for more, more, more. they see us as simply selfish. now we are at the forefront of the evolution of our species, psychologically and physically, and they don't like playing second fiddle AT ALL. ahem....pardon me.... and the SMART people understand all of this and can still find reasons to make our little existence meaningful enough to try as hard as they can to succeed amidst all the turmoil in this fold in time of human history. phew....so preachy huh. anyway, if you haven't figured it out yet, all i'm trying to say is.....
you're never going to learn anything about plants until you've learned everything about yourself. cut any leaf you want off.....take chances. just remember what you did so you can compare it to the results. be alert and aware to what your plants are telling you. do research. keep posting on riu. don't listen to scientists. they assume they know more than you about everything.