Around 12 calls if I remember correctly. With the exception of those who ghosted me, every company was very prompt, respectful of my time, and had a reasonable process that went from first to final interview pretty fast. I got a ton of outright rejections to my resume, which I sent around a lot. Getting the first call was the hardest part. YC job board ultimately led to finding my new role.
The company I went with had the best, warmest process that reflected how they like to work and was built to find people who had overlapping priorities. Thinking back, I think that most companies either deliberately or inadvertently wind up with processes that sync up with how they are organized internally and what kind of people they hope to hire.