I stopped using a stop bath when developing B&W film a few years ago. Given the cost of film (5x4 and 10x8) and the even higher 'cost' of the time to shoot I decided to stop trying to save a few pennies by reusing chemicals and dump them after processing. I find 500ml of dev and fixer for 10 sheets of 5x4 or 5 of 10x8 in an expert drum gives me consitant results with one less step to cock up. I do still wash between the steps when processing E6 though.