Never attribute to malice that which is adequately explained by incompetence / Nicht der Bosheit zuschreiben, was schon durch Inkompetenz erklärt wird – Robert Hanlon’s Razor 1980 (or Heinlein?)
Less is more / Weniger ist mehr – adopted by Ludwig Mies van der Rohe 1947 (1886–1969), earliest source probably Robert Browning in his poem ‘Andrea del Sarto’ (1855; it appears there on the 78th of 269 lines…)
The sum of all vices stays constant / Die Summe aller Laster bleibt gleich – personal observation
Months in the laboratory can frequently save hours in the library – Frank H Westheimer