The question behind the question
Most owners asking this are really asking: am I about to spend money that buys me two years or twenty?
Signs the roof is nearing the end of its service life
Corrosion at fixings and laps rather than in one isolated area. Repeated repairs in different locations. Flashings and junctions failing across the roof, not at a single point. Substrate or timber issues discovered during repairs.
Signs a repair is reasonable
A single identifiable failure point, sound material elsewhere, and detailing that is otherwise intact. A proper assessment should be able to demonstrate which of these describes your roof.
