a never ending subject ...
Deadly-Bagel wrote:... Well the issue ... is clarity and intuitiveness.
I notice the Wiki has now been updated to explain they always insert onto the right side from the belt's perspective ...
Now that the behaviour is explained correctly there shouldn't be a problem ...
just tested with the newest version 0.16.37 :
(marked cyan)
- when dropping items on a belt facing or opposing the inserter, they go to the right side
from the belt's perspective
- when dropping items on an underground belt facing or opposing the inserter, they go to the right side
from the underground belt's perspective
BUT:
(marked green)
- when dropping items on a splitter along the splitter, they go to the right side
from the splitter's perspective,
and to be more exact to the "far right" corner
from the inserter's perspective, thus not being split
- when dropping items on a splitter opposing the inserter, they go to the LEFT side
from the splitter's perspective,
and to be more exact to the "far right" corner
from the inserter's perspective, thus being split

- SplitterDrop.PNG (299.06 KiB) Viewed 1091 times
in my opinion, there should be no different behavior of inserters depending on whether items are dropped on belts, undergrounds or splitters (or any other beltlike objects, assemblers or whatever).
thus i consider the current behavior to be a bug in any case, no matter whether people think the perspective should be that of the inserter (then belts and undergrounds are buggy) or that of the target (then splitters are buggy).
to have "clarity and intuitiveness", behavior of inserters should always be the same no matter what the target is, and IMHO most intuitive would be that robotic inserter arms always drop items from their own perspective without checking first what the target is.
this can IMHO best be achieved by specifying the drop location as
"far right from the inserter's perspective" (just like it is now with splitters, marked with green dots in the screenshot), and this should even reduce the number of rules to a single rule for perpendicular as well as parallel inserters.
edit: new screenshot, and thus i discovered that for belts and underground belts, the drop location seems to be the entire right side (because the plates seem to fill the entire length of the tile and not only from one specific drop location to the end of the tile)
ps:
for me, the drop location isn't a big problem since i am mostly using bob's adjustable inserters and thus can adjust that position however i need it for a specific setup. but i still would want to have a single simple rule as default so that i don't have to check for problems and adjust the drop locations as often as i have to do now.