The origin of 多多益善 is a famous historical anecdote involving Han Xin (韩信), one of the most brilliant military strategists in Chinese history who helped establish the Han Dynasty. The story goes that the first Han Emperor, Liu Bang (刘邦), once asked Han Xin, “How many soldiers do you think I am capable of leading?” Han Xin replied, “Your Majesty, perhaps one hundred thousand.” The Emperor then asked, “And what about you?” Han Xin confidently replied, “As for me, 多多益善 (duō duō yì shàn)“—the more, the better. This story imbues the phrase with a sense of confidence and great capability. It's not just about wanting more, but about having the skill to handle more.
多多益善 is a very common and versatile idiom used in both formal and informal contexts. Its meaning is straightforward, so it's easily understood by everyone.