Three months to complete a Staff Software Engineer interview process is far beyond what I would consider reasonable. The extended timeline, combined with slow feedback and a lack of urgency, left the impression of a disorganized hiring process. The interviewers themselves were professional, but the overall candidate experience was frustrating and inefficient.
For senior engineers with multiple opportunities, the time commitment may not be worth it. I would recommend that the company significantly shorten its hiring cycle and communicate expectations more clearly throughout the process.