I think your imagination decided to rapidly overcomplicate what is literally (literally literally) Queuing Theory 101 example

If I were to guess there weren't any "backend servers" at all. It was just array of random increasing numbers (that stand for request arrival times) and arrays of numbers with minimum distance (that stand for time each consumer took a request)

there's no connections to "least-ify" the strategy about. There's no difference between consumers, no matter the amount of requests having been processed