Or what happens when Goldilocks runs elections. You want enough candidates to have a good number of choices but not so many you can't keep track of all the candidates. One candidate is out, unless you are in a dictatorship that pretends it's not. Two candidates can give you 2 who are polar opposites or you can have just another pair of dwiddle dee and dwiddle dumb. Three candidates is better but is still a limited number of choices. Four gives an acceptable number of candidates. Is double digits, the big 1-0, too many candidates? Yes; and how about 9 candidates, too many; lets make it 8, still a big field; just 7 candidates, that's better but still kinda high. Is a field of 6 candidates the most that should be allowed in an election? Yes, a fairly broad selection without being too fragmented.
There you go, you want to avoid a limited choice of candidates without having a fragmented field of too many. Take the lower number for more important elective offices where you want to know the candidates better. The middle to open the field more and the high number for the most number of choices. For my neighbours to the south have the 4 candidates in the elections for Mayor, Governor and other state wide offices, and the President. For the 50 Senates (US senate & 49 state senates) have 5 candidates in the election. For the House of Representatives, lower House of the State Legislatures, and municipal councils have the high number of 6 candidates to give the most choices.