I briefly worked as an accounting recruiter[1]. It's extremely plausible one person could be submitted to 17 different positions in a week, while another person gets one every other week.

Getting interviews is as much politics as it is being qualified. At the place I worked, recruiters owned their job listings and their applicants. You get paid more if you fill your jobs with your own applicants, for what I think are obvious reasons. Recruiters would only ask around for applicants if they didn't have anyone qualified for the role. So if the recruiter who interviewed you doesn't have a lot of job openings, and you are a pretty average candidate, you might not get sent out to a lot of companies, even if you are more qualified than other applicants.

On the other hand, if you have a candidate who has a great resume, you probably want to keep them for one of your own jobs as well. The candidates who got the most offers were generally candidates who had an uncommon background (and therefore would be difficult to place yourself) or who were liable to get hired before you could match them with one of your own openings. In that case you'd send an email to the other recruiters with a brief overview of the candidate (background, salary expectation, etc) and ask them if they had any openings for them.

In my experience, recruiters engaged in illegal hiring practices as well. For instance, if a company did/didn't want older individuals, you'd talk about whether they were interested in "seasoned" individuals (seasoned ostensibly being a reference to their experience) or set the experience required since college at [x] number of years, where [x] + 22 = the age of individual you were looking for. It was also well known which hiring managers wouldn't look at the resumes of women, or of individuals with "urban" names, etc.

Companies that were terrible places to work were always looking for "plodders" -- people who spent a lot of time between switching roles (4 or more years). The expectation being that they would be less likely to quit. Other companies really want people who are "climbers" -- people who tend to switch jobs or get a promotion every 18-36 months.

The candidates who got the most interviews were white males who went to a prestigious university, did internships, worked in a big-4 consulting firm for a few years, and then spent 1.5 - 3.5 years at each job after that point. They were referred to as "extremely presentable," in the sense that they almost always would interview well. Their recruiters would often send to interviews where the the hiring manager was asking for an amount below what the person was looking for though as a way of making the applicants available at a given salary look terrible in comparison. This would allow them to drive up the amount they were willing to spend and get some of the higher priced "average" candidates hired.

If you want a job, the best advice I have is to call/send emails to hiring managers at places you'd want to work, and ask them if they would be interested in a person with your background, or if they had any advice for you. Even good recruiters are mostly useful for negotiating salary (since the more money you make, the more they make), trimming the irrelevant parts out of your resume, and coaching you on how to do an interview. If you need help with the second and third points, you are probably better off paying for a career counselor, since they will have your best interests at heart. I suppose a recruiter might be a good choice if you have specific salary/benefits requirements and you aren't great at negotiating, though I've never really thought about that point since negotiation is probably my strongest skill.

[1] Recruiting accountants was the worst job I ever had. I knew nothing about accounting going in to it. Turns out I hate accounting, and talking to accountants all day was hell for me.