let well enough alone
Удовлетворяться тем, что уже и так достаточно хорошо; не пытаться улучшить что-то потому что часто это может все испортить.
John wanted to make his kite go higher, but his father told him to let well enough alone because it was too windy.
Ed polished up his car until his friends warned him to leave well enough alone.
Ethel made a lot of changes in her test paper after she finished. She should have let well enough alone, because she made several new mistakes.
Ср.: LET RIDE.