我想問 too xxxx too soon 點解

It is a very common expression. But the most famous one would be:
Too little, too late.
Too little too late is so famous that it is the name of a pop song.
好明顯，too xxx, too yyy 係講緊兩樣嘢但形容緊同一件事，too little, too late 之所以咁常用係因為好多時啲人發覺錯誤想補救但已太遲。
例: Tommy has just started studying one day before the examination and it was too little too late.
文法上 too xxx, too yyy 中間應有逗號，但由於已變成一常用 phrase，所以好多時都省略了comma。
Too much too soon 是 too little too late 的相反詞，雖然我揾唔到證據，但我相信是先有 too little, too late在先，因為人性弱點，too little, too late 的情況比比皆是。
任何 too xxx too yyy 都是按字面解就可以。

過快

過 於嚴重

太快太多
太快太嚴重