Make one useful decision
What to Do with Half-Used Notebooks

Review the information already inside a half-used notebook before deciding from its blank pages alone. You may be able to restart without copying everything or buying another notebook.
Identify useful records
Mark commitments, unfinished work, and entries you still refer to. A notebook with private or work information is not automatically suitable as a shared scratch pad. Check any original-record needs before discarding pages.
Choose a restart point
For the same purpose, mark the next usable page and note the notebook’s role. You do not have to fill every gap. Add a clear divider if a fresh section would otherwise be confused with earlier entries.
Separate a new purpose
If changing to shopping notes or practice paper, distinguish retained records from disposable writing. Consider whether sharing would expose earlier personal entries. An imaginary new use is not a reason to retain every notebook indefinitely.
An example and a stopping point
For example, mark useful explanations in an interrupted study notebook and label the next blank page “practice starts here”. If studying is still your goal, make this book usable before adding another purchase decision. Before discarding a notebook, verify that anything transferred can actually be found in its new location. Avoid tearing pages in a way that damages records still being kept.
A note for your own situation
Records to retain: Next purpose: Restart page: Suitable for sharing:
Keep this with the paper or digital notes you already use. No additional app is required.
For the related next step, see Meeting Notes: Separate Decisions, Action Items, and Pending Questions. Choose the guidance that fits the task actually remaining.