This is my biggest pet-peeve on my current project. I am a solo dev on my current project at work, and for some reason, we are still choosing to use agile/scrum with sprints and all that jazz (seriously, your guess as to why is good as mine).
Regardless, one of the more difficult issues I have encountered through out my current project is the usage of proper abstraction and avoiding redundency. I seriously have little idea of anything I build will for the project will ever be used again in a different part. Since, everything is given to me in sprints, I literally have no idea what is coming down the pipes.
Any feature I implement becomes an internal debate of how much abstraction is necessary vs. YAGNI.
I've since given up on even trying. Once the project is more or less finished, I'll properly just run back through it and then properly abstract, refactor, etc.. You know -- spend more time doing something twice than properly the first time, but whatever.