Time is money. You can't get it back, so you have to invest it carefully.
If you're like me, and have been publishing books into PDF format for years, it may be more difficult finding the original documents than thought.
On top of this, converting anything to ebook epub files is a rather tedious task of finding and correcting errors so they will be accepted.
Accidentally, I found a sequence which tends to create a very good ebook every time:
