Many two bath developers are based on D-23. According to the books - Anchell, etc - if D-23 is used straight, it should be replenished or used as a one-shot. Yet when it's used as the first part of a two bath, the conventional wisdom is use it for up to 20 rolls with no replenishment or extension of time. Does anyone replenish it or just use for 20 or so rolls and then toss it? Thanks.