What is the test for determining attorney's fees in a personal injury action?

On appeal, Greathouse argues that the district court committed legal error in declining to award fees on a flat-fee basis. A district court is granted "considerable discretion in determining what constitutes reasonable attorney's fees in a given case, mindful of the court's superior understanding of the litigation and the desirability of avoiding frequent appellate review of what essentially are factual matters. A fee award will not be disturbed absent an abuse of discretion." Matusick v. Erie Cty. Water Auth., 757 F.3d 31, 64 (2d Cir. 2014) (internal quotation marks and citations omitted).