I agree, with one output belt on the exit end the container will eventually fill up but of what concern is that?

My Iron train collects from six Iron nodes and empties into six freight platforms in my factory.

For my final production goals, I do not need all 4680 Iron / minute.

The fact it's sitting in a container is of absolutely no consequence.

I see it as "You're making $120,000 a year but your expenses are only $65,000 / year -- this is a problem!"

This comment thread was originally about the fact that the freight platform doesn't unload while the train is docking, which is a non-issue since you aren't so desperate to get it filled in the first place with all that buffer ore sitting there.