In just this one photo we have; non adhesive lined heat shrink, non-tinned wire, wire stranding for battery cable that does not meet the UL Marine spec for number of strands, oxidation already beginning, too much exposed copper from the wire stripping and a rather poorly executed hammer type crimp.
While this fitting did and does work the question would be for how long, and when, not if, would it have let you down? It should be noted that this cable was only two seasons old, located in a very dry area of the vessel and yet already beginning to oxidize.