Though players don't need to know this, I am using Sigg's task system hybrid.
In a nutshell, target numbers are in increments of four, just like the DGP system, except the 'typical' difficulty is 8+, just like the original CT success roll. DMs include the skill level (which is rated 0 to 6) and Characteristic/4 (rounded down).
So, you can see that the natural maximum from just those three items above is a roll of 12 + a skill level of 6 + a characteristic bonus of 3, for a total of 21. I don't expect a 21 to ever be rolled. The average total might be 10 to 12. Thus the average character will succeed at typical tasks most of the time.