Making the best use of the time

How's it done?  It is possible to capitalize on every minute, and if so, how is this done in a reasonable manner?  Furthermore, how much of my very application of this biblical notion is shrouded in American individualism and a hurriedness that people all over the world wouldn't even begin to factor in?

This definitely affects dreaming/planning/etc...

How much does it make sense to spend time writing a book if no one ever reads? 

How much does it make sense to pursue a doctorate if I'll never be able to use it? 

How much does it make sense to learn to play guitar or piano if there will not be a need for me knowing it? 

How much does it make sense for me to cultivate skills in calligraphy if I can pay people to do it better? 

How much does it make sense to write a study of some kind now when I'll (hopefully) be wiser and write one better years on down the road?

Is WANTING to do any of these things a good enough reason to do them?  Would doing any of these things for the sheer pleasure of doing them be a waste of God-given time that could have been used better?  When you factor in the truth that time spent doing any one thing is time that cannot be spent doing another thing (duh), it seems that simply doing something because you want to do it is not a good enough reason.

If the thing I am doing will never be used, if it has no purpose, should I do it?

No.

But what qualifies as purpose?

Catharsis, gifts, knowledge, expression, rest. Are these purposes enough to outweigh the purposes of other things I could be doing?