Maps are updated six times every day. The map update is part of the month processing that runs six times each day.
however,
if we run this for each and every slight change, the process might need to repaint all the maps six times each day. It might cause major overloads.
Each change carries some weight. the larger the changes, the larger the weight of these changes and they are added up per country.
once some thresh hold is exceeded, the map will be repainted.
as a result, a major change in roads or rail, or in population that results in a new city etc. will immediately trigger a repaint.
very slight changes will accumulate in time and then cause a repaint.