It indicates taking the lead in a situation, like managing a project or guiding a team. With the manager ill, I was in the saddle, ensuring the project met its deadline.
Pro Tip 2/3
Authority Connotation
Used to emphasize control and authority in a professional or personal context. She's been in the saddle of the marketing department for years, driving success.
Pro Tip 3/3
Not Literally
Even though it sounds like horse riding, it's about control, not actual riding. He took over the company last month and is now firmly in the saddle.