There are only two kinds of consultants→

Alan Weis has this to say in The Case for Value Based Fees in “Stubborn” Professions:

There are only two kinds of consultants: Those who think the input side is important, who stress methodology and bill by the hour; and those who think results are important who stress outcomes and bill based upon value contribution. The former are lucky to make $250,000, the latter make seven figures. The former are known for their implementation, the latter are known as thought leaders.