The reason for conducting a fresh census before the decennial requirement is because the government was unable to solve the problems inherent in the last one in 2017. That census was not formally notified because of objections by the Sindh government, and thus the next general election will either be conducted according to the previous delimitations, based on the 1998 Census, itself late. A new census this year, as Prime Minister Imran Khan proposes would bring the country back to having censuses in years ending with 1, restoring a sequence started by the British in 1872. While the census determines both, distribution of resources to the provinces, it also determines the delimitation of seats. However, there seems no real justification for reducing the intercensal period so drastically.
It would be much cheaper to remove the objections to the census, primarily from the Sindh government, rather than conduct a fresh census. There is no guarantee that the same objections will not be raised, that there has been undercounting or overcounting in one area or another. The expense of re-enumerating a sample of census blocks should solve the problem, but as time passes, that solution will probably not be available. As the census results determine the allocation of seats, the parties have vested interest in raising objections. The last two censuses had the Army providing enumerators, but it is unlikely now that the use of the military would not cause the opposition to claim that there was some gerrymandering being done.
Perhaps most crucial is the government’s ability to perform such tasks. It seems unlikely that a government which was unable to notify the last census would be able to conduct an uncontroversial census. The nation could find itself having to have a constitutional amendment passed to stop the constituencies reverting to the pre-2017 delimitations. That is not something that the government should look forward to, but it seems that that may happen. The PTI would not like to conduct a 21st century election using 20th century delimitations.