Good advice from Deb. I really don't have much advice since I am one of the lucky ones. My Bentley trained quickly, but he still has his moments. As a matter of fact a nice 1&2 accident right in the hall this morning after successfully using his pad.
I totally understand not being able to stay right on top of him. You might have to restrict his world a bit. Bentley will be 5 months on Saturday and he still does not have full access to the apartment. While I was training Bentley he was in a Xpen unless I was able to be right with him.
And YES your Bentley is smart. Any little boy name Bentley is incredibly smart.