i also remove any leaves if the stems break with a light tug. anytime part of a leaf turns brown though, it won't turn back to green. so i cut it. only if it's a significant spot though. i dont waste time cutting off little burnt leaf tips or real small spots. when part of a leaf is dead, that dead part is no longer receiving light nor are the stomata any longer active. it's kinda like when you have a scab over a wound that is ready to come off. removing it may make virtually no difference in plant health or growth, but it does look nicer. or kinda like when a hatching chick is having trouble getting out of the egg, just giving it a little help.