[osmanscam]

Answer of this question may vary depending on your goal.

Ask this question, in the way you describe here, to the person you are reporting to, who is responsible reviewing your annual performance. Depending on your target, you may say yes to all and ok be late for deadlines and no to everything else and just focus on one task, and deliver before the deadline.

However, answering colleague's 5-15 minute long questions is different then the above. You should do it even in the expense of doing overtime. If it takes longer then that, you should return to your work.