So rollup field works on contacts, leads and accounts but the limit of 10 per entity when most will want to count oppty closes, wins, loses, etc. can be limiting as well as the timing delays. Having a field already do this that can work with flows would be great. The other blockers with flows are:You cannot start with a modified record trigger for activities entity; you would have to start with each activity and then difficult to use more than regardingregarding is not consistent, regarding doesn't always show the contact in a tracked emailCannot create an action on a rollup field so for me while I can create a rollup for a contact by example I cannot then on modify of that rollup field have a flow check if the owning business unit is X and then add that date to a fieldSo we need to be able to have a rollup like field with cascading activities we can create action on or: fix rollup to allow for business unit and other filters or fix the activities entities to be more universal and work with flows or fix the ability to rollups to work with flows. Any one or more of those would make use of last activity in D365 CRM a super effective tool! That was many hours of research to find a simple way to handle using basic last activity by business unit solution! Thank you for considering and happy to chat more about this issue.