Plans must be comprehensive to avoid losing sight of one thing while tending another.
Tips
history
From Feng Menglong's 《东周列国志》 (Ming): the military stratagem of splitting an army and attacking from multiple directions forces the enemy to '顾此失彼' — defend one front and lose another. Still common in strategy and management writing.
grammar
此 ('this') and 彼 ('that') work as a pair — an abstract 'one thing vs. another'. They do not take concrete referents; you don't say '顾这个失那个'.
