What happens if after one finished the koshering meat/chicken, they remember that they forgot to put salt on one area?
The Shulchan Aruch 69:4 rules that preferably one should salt the meat on both sides, but if one failed to do so, the meat is kosher. However, the Rama rules that under normal circumstances one should consider the meat non-kosher. Under extenuating circumstances, or in case of great loss, the meat is kosher (Taz). When salted on both sides but missing a small area, some treat this as if salted on one side, others [Shach 20] treat this more leniently and permit after the fact even according to the Rama.