A dictionary of Proverbs (Oxford Paperback Reference)

LESS is more

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  1855 R. BROWNING Andrea del Sarto 1. 78 in Poems (1981) I. 645 Well, less is more, Lucrezia: I am judged. 1947 P. JOHNSON Mies van der Rohe 49 As in architecture, [Mies] has always been guided by his personal motto, ‘less is more.’ 1984 O. BANKS Caravaggio Obsession III. iii. Anyway, he spent years furnishing it with precious, ornamental works of art. This was in the twenties and thirties, when ‘less is more’ was the golden rule. 1989 Time 20 Feb. 108 What Chiat and his associates seem to be betting on is that there is a mass market of low-income, style-conscious people who have grasped the hip message that less is more. 2001 Washington Times 3 Aug. A17 It was as if the pink flamingos had been taken off a Florida lawn, the sequins off Dolly Parton’s cowgirl costume, the fins off a ‘50s Cadillac .. There are times when less is blessedly more. ■ moderation
  

less see also of two EVILS choose the less; more HASTE, less speed.
LET well alone
Well is normally considered here as a noun (’what is well’), rather than an adverb. The proverb is also frequently found in the form leave well alone.

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  c 1570 Scoggin’s Jests (1626) 76 The shomaker thought to make his house greater. .. They pulled downe foure or fiue postes of the house. .. Why said Scoggin, when it was well you could not let it alone. 1740 G. CHEYNE Essay on Regimen p. xxxvi. When a Person is tolerably well, and is subject to no painful or dangerous Distemper, I think it his Duty..to let Well alone. 1822 M. EDGEWORTH Letter 12 Jan. (1971) 317 Joanna quoted to me the other day an excellent proverb applied to health: ‘Let well alone.’ 1829 T. L. PEACOCK Misfortunes of Elphin ii. This immortal work.. will stand for centuries. .. It is well: it works well: let well alone. 1985 R. R. IRVINE Ratings are Murder xx. I don’t think it’s ever a good idea to tamper with tradition. Leave well enough alone, I say. 2002 Washington Post 17 May B6 From what I can tell, most people are members of the ‘Let’s Leave Well Enough Alone’ and ‘If It Ain’t Broke, Don’t Fix It’ clubs. ■ busybodies; content and discontent
  

let see also let the COBBLER stick to his last; let the DEAD bury the dead; let them LAUGH that win; LIVE and let live; let SLEEPING dogs lie; SPARE at the spigot, and let out at the bung-hole; never let the SUN go down on your anger.