If you're not employed and you want the best comp you can get, you should treat it as a full time job. My last job hunt was probably ~40-50 hours a week for a month between wrangling recruiters, hiring managers, and the interviews themselves... But I was absolutely haggard by the end of it and made sure that the hiring managers knew early that I'd need a few weeks between when I accept my offer and when I could begin.

I had direct contact with 31 companies. Of those, 16 made it past the recruiter+tech screens. We're about 2 weeks into the job hunt and at that point I needed to start pruning. I had frank conversations with the hiring managers and recruiters about comp, work/life balance, and how tight scheduling would need to be for the following interviews. This narrowed it down to ~8 companies. I also told them all they'd need to wait for ~2 weeks so that I could finish up all of my on-sites before I'd accept or reject their offers.

I scheduled on-sites over the following 2 weeks. Because all of the hiring managers and recruiters knew I was in 8 on-sites, they all tried to give me quick and good first offers hoping that I'd take it and drop my following interviews. A few tried to pressure me into a 2 day decision window (surprise, these offers were the lowest by far).

Of the 8, I received 6 offers. I failed the Google on-site and I turned down another company because of work/life stuff that came up during the interview. As offers came in I could decline ones that were clearly too low. The very last company that I interviewed with had the best offer, so I was pretty happy that I stuck it out... But the only time I was more exhausted was when we had a newborn in the house.

Depending on how you count "interview", these was easily in excess of 40. Each on-site was 3-6 interviews back to back.

I was happily employed, but wanted to stress test this strategy (and keep myself sharp, as practice in case anything did happen), and several years ago I did. Between a Wednesday morning and a Friday afternoon, I had set up over 40 interviews in the 2 week period starting the following Monday. I additionally scheduled a few more on Monday, for a total of 50+ round 1 interviews. I don't remember the exact numbers, but I had low double digit round 2s and single digit round 3s scheduled as well, with many more round 2 requests in the weeks following the resolution of this test.

It was exhausting, and the exhaustion scaled nonlinearly. By the end, I cancelled the last 5-10 first interviews, and all of the second/third round interviews. I did so with the same tact I recommend regarding replying to recruiters, and made no bad blood in the process. Several of the recruiters got such positive feedback from some of the clients that they told me I was welcome to apply again whenever I was ready.

Doing even 10 on-site interviews is incredibly draining, especially if you're actually contributing at your full time job.

I interviewed around 2 years ago at about 10 places as well. 10 days of interviewing for 6-7 hours was so mentally exhausting that I just took a week of vacation after all the interviews were done.

I had my 10 interviews in a span of 3 consecutive weeks.

I did about 30 interviews last time I was job hunting. It wasn't all at once, I would interview in waves: at most 3 final interviews a week. Doing that along with a full time job is definitely tricky, but with virtual interviews its manageable to stuff it in to your schedule.

There are a few reasons why I did this:

* Unless you have a strong connection or are industry (semi) famous, you're gonna get a _lot_ of rejections from most companies. Interviews aren't a very good way of assessing suitability for a job. You might get the wrong folks, interviewer or you might be having a bad day. Generally a single interviewer can tank the candidate with a thumbs down.

* The _only_ way to negotiate is with another offer in hand. This is just industry policy. Recruiters will tell you to your face that they are powerless to change the offer unless you give them a competing offer. Under these circumstances, you're forced to get as many offers as you can, and then play them against one another.