This is an interesting topic because there is really no short answer to this question and the answer is really dependent on your needs and the level of detail that you are looking to reach.
First, there are reports that come out of the box: Neglected Accounts, Neglected Leads and Neglected Cases. These reports, “display only active leads, with no activities or notes, in the number of days specified by the person running the report.” A reference:
Explanation of Neglected Leads Report
When I polled CRM Dynamics MVP, Richard Knudson, about these reports, I found that these reports have the following limitations:
1. These reports ONLY look at activities and notes, and do not take into account changes on the record itself. So if the primary contact, address and phone number were all updated yesterday but there haven’t been any activities or notes in a year, it would still be “neglected”.
2. They also do not take into account non-standard activities. For example, if in your database, there are email activities actions for a third-party email add-in, these records are considered neglected even though they have email actions (opens, clicks) during the period.
3. The actual queries that these reports are running is defined behind the scenes and there’s no way to see what’s being included or tweak it, and certainly not to create it for different entities.
So, we are back to the question on how to report on Leads (or any other entity) that have truly not been acted on in a specified time frame.
Another limitation in Microsoft Dynamics CRM 2011 is allowing you to do queries on NOT conditions. For example there is no way through the User Interface to determine which Leads have had no activities during the last 30 days.There is a workaround in which you could use marketing lists as follows:
1. Build a Marketing List for all Open Leads that have had activity in the last nine months.
2. Open the Marketing List and then Remove the members that have had activity in the last 30 days. This will leave you with Open Leads not contacted in the last 30 days.
See this link for more information in using this method: