When a roof leak returns after a patch
A patch that briefly settles a leak may have covered only one part of its path. Water can enter beside the patch, behind a wall covering or through an upstream lap. Sealant can also separate from a moving or deteriorated surface.
A useful second look asks what was repaired and what the water still has a route around. At a roof-to-wall joint, the answer may involve the hidden flashing and wall barrier. At a pipe, replacing a split collar can make more sense than adding another surface layer.
The repair price follows that access and reconstruction work: the detail, surrounding materials and damage below it. Repeating a smaller patch is not necessarily the cheaper choice when it leaves the cause in place.