I've just created a new Physical Standy for one of the Oracle Databases.

Using the query below I have put this into a SQL Developer report as a BAR_VERT_CLUST chart.

Then by setting a refresh interval I was able to monitor the graph to see when all towers where the same size.

From the chart you can see that if did not bother to retrieve the oldest archivelogs known to the primary. And some day's didn't map exactly.

But a nice use of SQL Developer reports to give a quick overview of whether the archivelogs sent to standby are up to date.

I've also posted a snapshot showing another Database that has been running for a while with a physical standby.