I can post one experience at least. A friend of mine asked to take the written test from the book "A look at Canada". Officer shared the results with him right after the test that he passed. After the test officer asked about his passport and Landed Immigrant Paper. My friend had the passport with him but left the Landed Immigrant Paper at home. My friend told me that he could see the naturalization certificate in officer's hand and also everybody on that day have taken the oath after the test and got their certificates except for him and his wife. He later got a letter from Montreal Citizenship office asking him to produce tons of documents, e.g. Lease agreements, hospital records, tax returns, school records for children, immunization record for children, any proof of property if he has one, etc. and was asked to appear before immigration judge. He and his wife submitted all the documents and appear before judge after about three months. After the interview with the judge they received a letter after another three months that the judge was satisfied and the judge approve their case and asked to couple to show for the oath ceremony. The oath was taken and the certificates were handed out. The whole process took approximately one year.