I usually add .1mm to bigger stones say 1ct and above when I cad. If your making masters it get even trickier then as there is lots more shrinkage going on. Also the shrinkage is across the mass of the metal so the thickness shrinkage is not proportional to the size shrinkage etc. As Dennis said add more meat to the settings so you have more to go at when setting. For pavé the seats are usually reduced to around 80% of the stone then burred to size by the setter. It depends on what your doing I have remade lots of rings before I got my eye in and I'm sure I will remake lots more.