This applies to scenarios where making a workbook a shared file so everyone can edit at the same time isn't feasible
Sometimes when multiple people are trying to work within the same workbook, the person who is currently working in the spreadsheet will forget about it if multi-tasking and doing other things. The other people waiting have no idea if the other person is actually still working in the workbook or forgot about it or worse, is away from their desk. A solution to this would be to create a reminder that pops-up in the workbook with two buttons after 5 or 10 minutes of no activity in the workbook. The pop-up would ask if the user is still working in the workbook (response button 1 could say, "Yes, I need more time" or if they're done, give them the option to save and close out (button 2 could say "No, I'm finished.") Incorporating this into Excel and even other Microsoft Applications (word, PowerPoint, etc.) would be more efficient and encourage people in the workbook to be productive and not delay making their changes/updates.
Divya Puri commented
Daily task reminder is a great value add