Power has to be energy put to a good use.

But at least she had made good use of them.

At least she had put the time to good use.

He had made good use of the last few days.

But I'll try to put the knowledge to good use.

Which is not perhaps a very good use of time.

And I actually make pretty good use of the time.

He decided to make good use of his five minutes.

He has even been able to put his medical training to good use.

We should, at any rate, be able to make good use of the time.