I'm not asking about sheer savefile size, or latest-developed 17-rockets-per-second zaftig-megabases.

I'm asking about the longest, point-to-point, single-journey train ride ever achieved or accidentally happened upon, whether by reason of intentionally creating it to goof around in a creative-mode testbench save, or organically growing from some sort of multiplayer shenanigans, or anything else remotely similar.

I'm trying to figure out some of the hypothetical upper limits of Factorio gameplay, and for other reasons that would really bloat this discussion and scare away commenters, I'm also secondarily interested in how those hypothetical upper limits might have evolved with the various version pushes of Factorio.

Current thought process starts from the "Camel and 3000 bananas" problem. In that scenario, a person owns 1 camel and 3,000 bananas, and needs to deliver 1000 bananas to a destination exactly 1000 km away. The camel has a maximum single-load carrying capacity of 1000 bananas, and to move, the camel itself needs to consume a new banana for every kilometer of distance traveled, including every kilometer traveled on the return voyage back to the start location to pick up another load of 1000 bananas. In that math problem, bananas can be "dropped off" in a pile at any location along the journey and the bananas will neither rot, spoil, nor be stolen by humans or animals. Any amount can be amassed, deposited, or withdrawn at any single location, so long as the camel retains in its inventory sufficient bananas to complete its intended journey.

Theoretically, pre-distributing single individual bananas at 1km distance increments for the entire length of the intended travel will allow the camel to consume an individual banana from its own inventory every kilometer and then withdrawing those pre-distributed bananas up at every kilometer-marker to top off its inventory back to the maximum of 1000 bananas carried.

This word problem can be varied, including the idea that banana supplies at the start location are theoretically unlimited, or even some forms of parallel-haul mechanic where quantities of bananas can be invested into the procurement of additional camels. Change "camel" to "fuel tankers," and switch out bananas for liters of diesel fuel that fuel tankers require to run (or food for human workers, or water, or medical supplies, etc.) and this same problem is an entry-level logistics riddle for teaching the techniques of complex operations, with both civilian and military real-world applications.

I'm attempting to apply that riddle to a Factorio context. My holy grail in this is to develop a lesson plan for college students that involves Factorio gameplay to demonstrate proof-of-concept considerations.

I understand that in Factorio, the highest energy-density possible in a single stack of fuel is 1.21GW in a single non-stackable unit of nuclear-fuel. Prior to nuclear fuel existing in the game, the highest achievable was 1GW in a stack of 10 units of rocket fuel. Energy-utilization calculations in trains and train locomotives has changed a few times depending on how many versions back we might look for an example. Despite that, I know of know specific edge-case scenario (regardless of YouTube, this subreddit, the game forums, the Steam forums, etc.) where this upper-limit fuel capacity was even remotely at risk of becoming a problem that needed to be solved by a player.

I'm asking if there are any examples anyone can describe to me -- whether with screenshots, video footage, or even old savefiles, where this can kinda sorta be argued was a thing that needed worrying about on an in-game basis. This means that a map can either be accessed directly via savefile for benchmarking, or can provide any evidence to suggest by observation, that a single-journey train voyage without any pit stops along the way consumed any appreciably high proportion of a locomotive's internal fuel capacity, such that refueling at the destination was physically required in order to ensure that the locomotive was able to return at all to the beginning of the trip.

Thanks in advance, folks!