It's more complicated when you have many types of item and not many of each item, because a filter inserter can do five types and a splitter can do one.
And if you add some wires, you can have each inserter automatically grab whatever is directly in front of it that isn't on a blacklist. At that point a max-throughput build with inserters is a big but roughly fixed size, while a build for splitters is proportional to the number of items.
And if you add some wires, you can have each inserter automatically grab whatever is directly in front of it that isn't on a blacklist. At that point a max-throughput build with inserters is a big but roughly fixed size, while a build for splitters is proportional to the number of items.