It took awhile for me to figure it out; but I discovered that 1:15k really disagrees with me. You're not alone!
Unfortunately, it's not all 1:15k maps; some of them are just fine! So I have no way of knowing ahead of time how bad it'll be. I guess this time I did have a way of knowing, since I went out on the model and was like, crap, I can't read this.
I do like that the paper size is often smaller, since I have small hands, and when the paper is massive I have to fold it a gazillion times and my left hand actually gets tired from this .