I’ve have had enough bookmarks fall out of the book that I have changed my strategy. Instead of using a bookmark I take a photo of the last page I was reading before closing the book. I then add the photo to favourites so it’s easier to find. And then later when I continue to read, I check in my camera roll to see what page I was on. With the current book I am reading I also like to end on the end of a chapter when I can. Easy to remember that next time I will start reading chapter 5 or whatever. And if I don’t have time or energy to read to the end of a chapter I still try to remember what page number I am on, just in case my phone runs out of battery and I want to continue reading.
[0] https://www.google.com/search?udm=2&q=%E6%9B%B8%E7%B1%8D%E5%...
[1] https://imgcp.aacdn.jp/img-a/800/auto/aa/gm/article/4/1/4/9/...
Compare that entire rube goldberg machine with one button press on an e-reader.