The current catchment area for passenger stations has a radius of 12 tiles. But if I understand it correctly, the walking time from the house to this stop becomes part of your overall travel time and thus decreases passenger demand. Ideally you'd have a stop at every house, except that loading times would slow down everything to a halt. Finding a good compromise is difficult, because demand depends on travel/waiting time and distance from the stop is as important as convoy spacing and speed.
I seem to have developed a habit of placing one every 10-12 tiles, which means a 50% overlap. How far apart do you place your stops?
Passenger success ratings for single houses doesn't seem to help me much, either. Unless it could be shown as a colour-coded display; not in the map window, but the normal display (as in the shaded "Shift-2" mode, where industries are red/yellow and public buildings green), with each each house shaded a different colour depending on passenger success rating. The shading mechanisms are already in place, the success rating is calculated, too, and it would help James fight the long, boring afternoons. What do you think?