This came up in this question: What's an efficient way to handle magical item identification?. Many people suggested taking 10 on Spellcraft checks to identify magical items. I certainly see the appeal—but is it possible in all cases?
I thought that taking 10 or 20 was only possible if many attempts could be made and failure was not harmful (or if it was, the character accepted the harm). Since some magical items could be cursed or booby-trapped, it seems that trying to identify the item could be enough to trigger its harmful effects. By trying to identify such items, a character may be in "immediate danger" without knowing it. Does this mean that one cannot take 10 or 20?
For convenience, here’s what Paizo says about it (link):
Taking 10 and Taking 20
A skill check represents an attempt to accomplish some goal, usually while under some sort of time pressure or distraction. Sometimes, though, a character can use a skill under more favorable conditions, increasing the odds of success.
When your character is not in immediate danger or distracted, you may choose to take 10. Instead of rolling 1d20 for the skill check, calculate your result as if you had rolled a 10. For many routine tasks, taking 10 makes them automatically successful. Distractions or threats (such as combat) make it impossible for a character to take 10. In most cases, taking 10 is purely a safety measure—you know (or expect) that an average roll will succeed but fear that a poor roll might fail, so you elect to settle for the average roll (a 10). Taking 10 is especially useful in situations where a particularly high roll wouldn’t help.
When you have plenty of time, you are faced with no threats or distractions, and the skill being attempted carries no penalties for failure, you can take 20. In other words, if you roll a d20 enough times, eventually you will get a 20. Instead of rolling 1d20 for the skill check, just calculate your result as if you had rolled a 20.
Taking 20 means you are trying until you get it right, and it assumes that you fail many times before succeeding. Taking 20 takes 20 times as long as making a single check would take (usually 2 minutes for a skill that takes 1 round or less to perform).
Since taking 20 assumes that your character will fail many times before succeeding, your character would automatically incur any penalties for failure before he or she could complete the task (hence why it is generally not allowed with skills that carry such penalties). Common "take 20" skills include Disable Device (when used to open locks), Escape Artist, and Perception (when attempting to find traps).