I think it was management that chose to go with a cheaper model, not the engineers. They got to think about profits.

You do realise that a neural net, given the same input, will always give the same output, if you set your random seeds of course. It doesn't depend on time of day unless you degrade the service when it is overloaded - say, you use a different model in the evening that is 10x faster but 2x worse.