It takes me a lot longer than four hours. Most castings need to be thinned down a lot to make them right. I use old dull files, which adds time. I like the get the facets just so, which takes time. The extensions need to have a reverse taper filed on them, don't forget. The inside of the bow needs some attention, too. It then takes me forever to get the file marks out with sandpaper(ulp, yes, sandpaper) on a wooden backer.
If I could stay at it full time, take no time off for coffee or 'checking the ALR', it might take me six to eight hours.