You shouldn't really compare the amount you take with other people as everyone is different, just use what you need
As a vague range though when I went on a carb counting course last year, one person used 1 unit bolus insulin to 2 carbs, one used 1 unit to 50 carbs - neither was wrong. It also will depend on how many carbs you eat, some eat more than others so that also would be taken into account.
@Rokaab@helensaramay@Muneeb thanks guys! Thats really put my mind to rest. From what my diabetic nurse told me I was under the impression these cartridges should last at least 2-3 weeks. But it appears my body just needs a higher insulin/carb ratio as I eat very little carbs... but then protein comes into the equation. I'm sure with time things will be a bit less confusing.