A while back I did this art test for Digital Extremes and used it as a kick in the ass to learn Substance Painter.
Original Estimate - 24 hours
4 hours Medium poly/blockout
4 hours high poly
2 hours low poly modelling
2 hours UV unwrapping/packing
4 hours baking textures
8 hours texturing
2 hours renders/presentation shots
TOTAL TIME - 26 hrs