I'm guessing you just finished a busy week and I'd bet that this one is shaping up that way too. Most every preacher I know struggles with time management. One of the things I love most about ministry is that every week, every day is different with many adventures. Some weeks you'll live at hospitals, others you'll spend many hours in counseling and some you'll have to sequester yourself in your study.
The truth is there is NO specific "plan" and you can begin to feel like you never finish, like you can't get it all done and have desperate feeling of failure. What we know is that you do what you need to do when you need to do it. We don’t put sprockets on thingamabobs or punch a time clock. We don’t see clients or patients. We don’t punch a clock or have quotas.
Yet, you’ll find yourself in certain patterns. My advice is pretty simple - work hard and relax. Our dad did his Sunday sermon prep on Saturdays and did it well. I know some guys who put their sermons to bed on Thursday and others who have a system where they spend part of each day with a specific aspect of the sermon. And sermons are funny "beasts" there are those I have put together so simply and even speedily THEN others I agonize over for MANY, MANY hours and even weeks. So to say "you need to put 10 hours of study in for every sermon" is not a fair statement. Some you'll put more than that in and some less. I’ve heard the story credited to many over the years but as far back as I can trace it is Dr. Lyman Beecher who delivered one of his most famous discourses and when he came down from the pulpit he was asked “Doctor how long did it take you to prepare that sermon?” “About forty years.” Yes, some of your best sermons will take a lifetime to learn and share. And some people have the mental capabilities that they can study MORE in LESS time (I wish for that "gift"). I hope that helps some.
Work hard…and relax. And God bless you - YOU work for HIM.