Coming from Japan to YVR in the past 15 years however YMMV.

We have carried about 1, 500,000 yen to ($14,000-18,000 CAD depending on exchange) a few times.

Each time, we filled out ONE declaration form as a family.

We were told twice by Canada Customs, "thank you for declaring especially when we were not legally required to". I usually carry about $8,000 CAD and wife carries about $7,000 CAD.

We always did because we also carry a foreign currency travel wallet which has a few hundred dollars of USD,EU,RMB,TWD etc which we are never sure the exact value and didn't want to be somehow be over the magical $10,000 limit.