I don’t think I would ever need 64 lines, but then again I don’t fish competitively. My armoury of lines is as follows:-
Salmon Fishing - 1 floater, 1 intermediate and 1 sinker. I also carry polyleaders in various densities which I use mainly with the floater.
Trout fishing on rivers, 1 floater and polyleaders.
Trout fishing reservoir, wild loch and other still waters 1 floater, 1 midge tip, 1 intermediate and 1 sinker. Also the polyleaders for a bit more versatility.
Taking into account the different weights of line I have around 14 to 16 lines that get fairly regular use and some as yet unused spares.
Having totted the lines up I have more than I thought I had, but I never carry more than 4 at any one time ie when fishing at a stillwater for trout.