To be safe just go on the number of days. Each working week where you work at least 30 hours is considered full-time. When you hit '365' days (including vacation, public holidays etc) that is 1 year.
Does it count as 6 years or 5 years, please clarify Company A: 4 years 6 months
Two different job positions held but in same NOC
NOC B: 2 years
NOC B: 2 years 6 months
Company B: 1 year
Company C: 6 months (Less than one year)