Caroline,
Keep the curiosity going, it will serve you well. The real paradox of SOP usage is this: When you need them the most, you'll be the least likely to use them. On a sunny day, with a routine trip and and competent crew, the SOP's are reflexively simple to use. On a difficult day, with ATC re-routes weather, and mechanical issues, a crew can find themselves "time compressed" to the point where the callouts and checklists are not being accomplished. The SOP's are designed to protect us in these situations, however we're most likely to not use them in the above described scenario.
A recent post-accident human factors study of several regional airline CFIT (controlled flight into terrain) accidents found some interesting similarities. In every CFIT accident you care to review, the mishap began with time compression. It's easy to say, "OK lads, don't get rushed.." but it was also discovered that the time compression was always followed by a broken habbit pattern, then a distraction. Imagine these as a triangle. When we're out aviating, we often deal with time compression, all part of the job. recognize however, that when you start to feel that "pinch" of being rushed, it's probably time to get downright religious about your checklist and callouts. Doing so helps prevent a routine distraction from causing a mishap.
SOP's are the cornerstone of safe flight operation. They affect everything you do. For example, a British Captain flying a 747 with an asian FO, may ask: "Ah, give me one-eighty on the airspeed please." If the FO doesn't speak any english but aviation english, the Captain will recieve no response. If the Captain points to the mode control panel and says" speed set, one eight zero", he'll get exactly what he wants.
Good luck with you career, enjoy the journey.