There is no rule for 1 year. You can stay outside for up to 3 in 5 years. If you want, these 3 years can be in one block or in bits and pieces of max 1094 days.
What some people may tell you is that you may not be outside Canada for more than 6 months in every 12. These are old rules which were replaced by the new rules in 2002 and the new rules say 2/5 years in Canada, nothing else.