A simplistic explanation of the developing process would be that one hydroquinone molecule reduces one silver halide molecule. In reality the process is much more involved. Infectious development can be thought of as a chain reaction whereby more than one halide molecule is reduced. Developing agents differ in how well they they support this reaction. Hydroquinone is one of the best and ascorbate ion is one of the poorest. In addition the oxidation product of hydroquinone is itself a developing agent. This is not true of ascorbate ion. Now the extent of infectious development is effected by several factors such as developing agent, sulfite concentration and pH. It is present to some extent in all developers. The reaction is maximized in high contrast lithographic developers. It is infectious development that makes the development process practical in that it amplifies things. Without it emulsions would be very slow. As with all things photographic there is a price and that is how well fine detail is preserved. Ascorbate ion is better than hydroquinone.

Ascorbate ion produces greater detail in all portions of the negative or print. In my own experience the difference is quite noticeable between hydroquinone and ascorbate ion based develpers.