The GM may modify your skill level to reflect the difficulty of a task. Your final skill level, after applying all modifiers for the task at hand, is your effective skill for that task. In nonadventuring situations when you have lots of time to prepare and face minimal risk, the GM may give you +4 or more to skill. (The GM might even declare such actions successful instead of wasting time on a skill roll; see When to Roll, p. 343). Ordinary people almost always receive this bonus at mundane tasks, even if they are working from default skill!
Example: An airline pilot has Piloting-12 – normally a 74% chance of success. For day-to-day flying, however, he rolls at +4. This makes his effective skill 16, for a 98% chance of success.