Most Recently Updated (MRU) refers to an option in the setup of the mappings (field and relationship) that determines how data will flow and which system has more accurate information.
By default, if you have a field at the top of the list, it will be considered the master and the fields below will never overwrite its data. While the data can never be overwritten, it is possible for the fields below to populate the master if that field is blank.
However, the MRU setting will change that behavior and instead of prioritizing the field at the top of the mapping (the SOR) we will ignore the order and prioritize whatever has been most recently updated.
For each field mapping, you have the option to check the Most Recently Updated checkbox. When saved with this option selected, we will always sync the most recent change that we read in from updated records.
Note: we will still not override an existing value with an empty value. All updated from a value of something, to a value of nothing, will be ignored to preserve data integrity.
A useful example for this may be Lifecycle Stage, or Status, or any other field that you want to make sure can and will sync back and forth between both systems. This is as opposed to fields that you know you need to prioritize from one system or the other.
Setting up MRU is as simple as opening a field mapping, clicking the Most Recently Updated checkbox, and clicking save.