We had a "long drop" when I lived in central Africa .. actually, the official title was the Blair pit latrine ... sure there's a political joke in there somewhere :)

This was a concrete slab with a hole (and typically some "organisations" set a metal bar across this to stop women putting unwanted babies down the pit - this happened at least once while I was there - in one case they couldn't get the baby out in time) set over two interconnecting pits - the first took the "solids" with a second, rock-filled soak-away, overflow for "liquid"... (the block we built for our staff also had the innovation of a shower that drained away into the pit)

What was part of the mystique of how they worked - admittedly, the "long drop" was at least 15 feet - was dropping a lump of meat down the first pit to get the enzyme action going. There was no smell, although more primitive versions of these were known colloquially as the "Chimbudzi" translated from Chichewa as "Houze of the goats"!

From the house we had an underground "septic" type tank which, for years, had never ever given a problem or been emptied. Until, we added a second toilet and dug it up to add drainage. And discovered it was completely empty and bone dry ... where "things" had been going for decades we never worked out ... but outside the bathroom we did grow spectacularly tall - 4 and half feet versions of the normally 12" bedding plant - Salvia.