There's a fine line sometimes. You break and enter, you steal something, you might commit a sexual assault, and there might be a robbery. There might be a number of primary designated offences in those acts, but if they were all connected they would only be able to count as one offence, for example, assuming you got a total of two years.
Today you can be convicted for a bunch of different offences you did historically--one in 1978, one in 1982, and one in 1985. Those would most likely be interpreted as three primary designated offences, because the acts were not connected in time and there was no nexus. So based on current jurisprudence, in that scenario the latter would have three primary designated offences qualifying for the presumption, and the former would not.