I dunno where this idea came from that one or two cavity moulds are easier came from, especially two cavities. I used them for years because that was all I could get and I struggled. One cavities have their place for rifle and other high accuracy applications. Two cavities are not only nearly as slow, they have the vice of all multi-cavity mould in that the cavities are not identical.
Eventually, I came into a nicely broken in (read well-used) Lyman four cavity and I never looked back. I had to cull, but I had to cull anyway. One bad bullet was no longer a wasted cast. I no longer spent two hours casting for every hour on the range. (I was shooting PPC at the time and you go through some bullets doing that.)
Then I got some 4 cavity aluminum block moulds from P&C and NEI. My production rate just soared. No more dumping the first six or eight casts straight into the sprue bucket, preheat on the pot, two casts into the sprue bucket and watch them good bullets pour out. By that time I was running two Lee ten pound bottom pours with one heating while I was casting from the other.
Then Lee came out with six cavity aluminum moulds for the price others were getting for a one cavity mould. I ain't worn one out yet and my bulk cast, hastily inspected .38 WC shoot 1"-1.5" groups at 50 yards from a Handi Rifle. I plain don't need any better bullets than that in a pistol and I doubt that many other folks do either.
As a side note, when I started using Lee pushthrough sizing dies, my group sizes shrank dramatically. Bullets sized that way still don't shoot quite as well as the ones I can shoot as cast, but I don't get the fliers I get with bullets run through a Lyman or Herter's sizer. Never used a Star so I can't speak to that. A good many serious shooters of cast rifle bullets will no longer use anything but the Lee push through.