We've mentioned on the forums that our script is unusually large for a Genesis RPG and a lot of that has very little to do with the core script. We've taken care to populate each city and town with lots of NPCs and unlike most 16-bit RPGs what they have to say is actually (GASP!) interesting.
We've treated each of the little guys as mini-stories. Stories that are unrelated to the core plot, but will nevertheless evolve with the main game. Most of them have multiple lines of dialogue in each "chapter" and then as events progress those lines change.
Usually there are a, b, and c sets of lines. So on average, we'd guess that each NPC has around 7 - 10 lines throughout the plot. We haven't looked at the NPC script as a collected whole, but I imagine it's almost as big as the core script.
You better actually talk to them or all that work will be for naught!