That could be a fun visual feature, to watch as paths and roads appear procedurally based on the layout of the town, but I don't think it's particular realistic, and might miss out on some strategic richness. Designing road networks is actually a complex and nuanced thing in and of itself, and it's certainly not as simple as "pave over the paths that people walk on the most." I think I would prefer road design to be a crucial part of the strategy in designing an efficient town.