I think one Elector would always vote for another candidate just to preserve Washington's legacy.
Maybe, but this never seems to have happened, even in 1820. William Plumer didn't vote against Monroe to preserve Washington's legacy of unanimity. He voted against Monroe because he thought Monroe had been a mediocre president and John Quincy Adams would be a better one. The classic article on this is unfortunately not available for free online for non-subscribers except for its first page https://www.jstor.org/stable/1897643?seq=1#page_scan_tab_contents but its conclusions are summarized at https://en.wikipedia.org/wiki/United_States_presidential_election,_1820
Plumer by the way was hardly unique in this attitude. His son later wrote, "This dissatisfaction with the course of public events was by no means confined to Governor Plumer. I was in Congress at the time, and saw much of it in that body. I received many congratulations on this vote of my father, from such men as Randolph, Macon, and other Republicans of the old school. Not that they liked Adams, (Randolph assailed him with the fury of hereditary hate); but they disliked Menroe, whom they regarded as having adopted, chiefly under the influence of Calhoun [remember that Calhoun was a nationalist in those days--DT] some of the worst heresies of the old Federal party. Randolph said in the House, with his usual felicity of sarcastic expression: 'They talk of the unanimity of his re-election. Yes, sir; but it is the unanimity of indifference, and not of approbation. Four years hence, he will go out, with equal unanimity; and the feeling will then be, not indifference, but contempt.'" https://books.google.com/books?id=O40ndLx4BowC&pg=PA495
Incidentally, a handful of Federalist electors were elected--unlike Plumer they all voted for Monroe (which somewhat confirms the Old Republicans' complaints about Monroe).