As an elder on a few occasions - usually immorality related ( affairs / kids fooling around. ) Usually confessions - open & shut cases - private reproofs. Some were a bit more complex - we had one where a couple had separated & the husband found out that his wife had slept with her previous husband during their marriage so it was escalated to a judicial committee to establish porneia & to discipline the sister (who was a "model pioneer" during all that time , often used on assembly demos & experiences).
Some of the elders I worked with were good , others were pretty useless. You get the old style kindly elders and the power hungry jerks. Frankly , most elders (myself included) struggle with JCs as they don't normally deal with enough to become reasonably competent.
Never dealt with apostate cases , though.