Optimizing LASTNONBLANK and LASTNONBLANKVALUE calculations
The DAX language can operate on aggregated values and on individual rows of tables in the data model, but it does not offer an immediate syntax to perform visual-level calculations over the cells visible in a report. The reason is that a DAX measure must work in any condition and in any report, which is why the notion of row context and filter context exists in the DAX language.
When you need to apply the notion of “first”, “previous”, “next”, “last” while iterating a table, you might have to struggle with these concepts in order to get the result you want. There are a few DAX functions that can simplify the syntax, but they must be used with caution in order to not hurt the query’s performance: