Accidentally this week and last week I did some non-standard thermal simulations with through-hole pins by imitating hot solder solder wave underneath the PCB. Of course a mere thermal simualtion can only look at heat spreading in detail but cannot cover metallurgical or fabrication aspects. Nevertheless, the results gave a correct agreement of positions of the problematic pins (and those without problems) compared to the solder wave result. Among other effects it showed that local copper around a solder pin can help heat to flow toward the pin rather than flowing away from it. But all that depends on details of the layout in the bottom layer and maybe in other layers as well, the mass of the component, how the flux is dispensed and many more influencing parameters. A numerical investigation can help to reduce the number of prototypes.