It's true. Textbooks are not essential for med school for the most part. You might just have like 1000 powerpoint slides for a test instead....ha ha ha. But seriously, this is a great question to ask. I'll share a little story about a place covered in Blue with little Devil's running around called Dooke Medicul Skewl block4:
We have a reading list with like 10 books on it for this block, one of which is a 1500 page path book. For the micro part of the block, we have three books listed, "none of which is perfect." So basically they assign three books and reading assignments from all of them and want us to spend like all day going through them to find out what is important [if you're wondering, it is sort of hard for someone who hasn't seen this stuff before to know what is important]. The only book we have this block that actually goes right along with the lectures and is a really good, easy to read book is our immunology book. I actually asked the course director is there was a shorter, acceptable book for path since I can't read and learn 1500 pages in 20 weeks. He said, "Well, you'll just have to read it sparingly." Talk about two people being on different wavelengths! So you think to yourself, "What in the world do I do?" Easy! Don't read the books except for the immuno book! You say, "But won't you fail out of school doing that????" Well, no one else is going to read a 1500 page path book either! There MIGHT be 3 students in the whole class that could pull that off, but I doubt even 3 could do it. And it seems that every year above us skipped out on using a path book and for micro used this book called Medical Micro Made Ridiculously Simple. So this is a tried and true way of dealing with this block I guess.
So this might have seemed like a totally irrelevant story that was a waste of your time. But there is a moral here: they WILL assign you readings that are a waste of time. Don't assume for a minute that just b/c you're not really going to use a book or that it is a big waste of your precious time most of the time that they won't TELL you to read the book. It's up to you to realize when reading is worthwhile. Most of the time they teach you what you need to know...