過ぎたるは猶及ばざるが如し (すぎたるはなおおよばざるがごとし): the last drop makes the cup run over; too much of a good thing; less is more

the last drop makes the cup run over; too much of a good thing; less is more

From the Analects: going too far is as bad as falling short. Useful for over-preparation, over-seasoning, and any effort that has carried on past its own best point.

A Japanese proverb (ことわざ)