When self-studying physics, retaining your problem solutions is generally advisable, as they can serve as valuable references for future studies. The organization and clarity of your work are crucial; well-structured solutions with clear notes and comments enhance their usefulness. As physics concepts build on foundational principles, revisiting earlier problems can aid in understanding more complex topics. While it's common to discard solutions that are poorly organized or unhelpful, maintaining a personal archive of your work can provide insights and reinforce learning. Ultimately, keeping solutions until they can be revised or improved is beneficial for long-term comprehension.