The oil press has a maximum continuous operating time of 20 minutes, so you can't answer the question like that. After 20 minutes of continuous operation, the press must first cool down before work can continue. As the OP 700 is not intended for commercial use, sequences of 20 minutes are absolutely sufficient.
As far as the amount of oil is concerned, this depends entirely on the quality and oil content of the nuts used. Both vary depending on the variety and growing region.
In the last practical trial, around 65 g of oil was extracted from 200 g of walnuts within a period of around 15 minutes.