How to find contacts that don't have any tasks or events
Less Annoying CRM has a filtering option to see only contacts that don’t have a task or event attached to them. If you go to the Contacts page, you'll find the filters and sorting options in the page menu on the left. Select "Add a filter."
Next, select “Tasks and Events” from the dropdown list. Then choose “is not attached,” to a “pending,” and “task or event”. You’ll also have an option to select a box to include overdue tasks.
Once you’ve made the appropriate selections hit Apply filter, and a list of all contacts without an associated task or event will appear. That's it! You can use this list to go through your contacts and attach tasks or events as necessary.