Alice,
I do not think that accuracy is the best term to use for the Leeds method, but convenience may be a better one. It is useful and convenient. Accuracy depends on the user more than the method. All it really does is serve as a way of sorting matches into groups, so when you have several hundred matches having a sorting method is helpful.
I find that trying to use Leeds on Ancestry Thru Lines is only barely useful as there are not enough codes available for my use. In a spread sheet, no problem and using Genealogical DNA Analysis Tool no problem.
I would suggest that you add your DNA test to Gedmatch - it is free and will help finding matches. And of course please add your family to Wikitree as soon as possible at least back to some open profiles.