I might work on your question in the meantime since I'm a charlover who recently came back to the game and I plan to do EVERY quest, even the useless ones like Alawar's Vault quest (when I started playing on 7.5, this was one of the quests that I did and it rings so much nostalgia) and then I can have more examples on which quests can be "missed". I like to have all quests marked "completed" on my questlog, and certainly will keep my attention to that detail.