For some reason, there is a one week gap between artist hosts. Dierks Bentley did the month of May, but his period was scheduled to end on Friday May 25.
Country Aircheck says:
"Arista's Lanco will host middays on Mt. Wilson's KKGO/Los Angeles June 4-29. The group is the latest in a series of artists to host the daypart."
My guess is the artist hosts work for 4 weeks, and May was a 5 week month.