@Ali ***********
most 1-year extensions for retirement are issued the same day you apply.
If it's for marriage there is usually a 30 day under consideration period where they may come inspect your home and talk to your neighbors.
More and more offices have been doing home visits for retirement extensions as well so that may involve an under consideration period if they decide they want to visit.
I don't think Australia offers that, you would need to check the embassy website.