Complex sentence: Since 1992, Allen has worked regularly, primarily in guest or recurring roles on various television series, including "Doogie Howser, M.D." and "Silk Stalkings".
Split into simpler sentences: Since 1992, Allen has worked regularly, primarily in guest or recurring roles on various television series. These include "Doogie Howser, M.D." and "Silk Stalkings".