For the small startups, who don't have time for BS like leetcode, I advise asking the candidate's code first of all. The senior-level developer almost definitely should have GitHub with his portfolio- or pet-projects. After carefully looking through his code, it becomes 100% clear do we want to talk to him or not. After that we usually had one interview, something like system design + soft-skills. Subjectively, I recall the hiring experience as very successful compared to what I experienced interviewing people for major tech companies according to their guidelines.