In 1990, the English commission recommended an additional constituency for the rapidly expanding new town of Milton Keynes. The review process can be quite time-consuming. The method of calculating the electoral quota produces a built-in bias towards an increase in the number of seats. The allocation of theoretical entitlements to local government areas also tends to inflate the number of seats. This is because fractional entitlements are often rounded up rather than down.
Different commissions can give different weight to the various criteria.
The use of the registered electorate rather than the population, although beneficial because the electorate is enumerated annually, means that two to three million people may not be included in the count. The local inquiry system allows the political parties to employ the various criteria to press cases which favour their electoral interests, without being transparent in their reasons and often using very spurious cases. Thus the strength of the advocacy may convince the AC, rather than the merits of the case.