When I have an important task, I postpone everything else. What should I do?

Have you ever heard of Getting Things Done? There are many famous/executives/successful people who follow those techniques. It might be worth checking out.

You have to multi-task. Dropping everything to do a job, is fine as long as you are very organized and focused.

Does it take a full 18 hours day to do the one task? How many hours does it average to complete a task?

Put things like doctor appointments on a calendar and take time off from work to visit them.

Delagate easy routine tasks to a subordinate.

You can’t be that one sided. Ask yourself if your work is more important to you than the people in your life? If so, continue as you were I guess