First understand how agencies actually work. Unless it's 110% obvious you'll get placed withing a pretty short space of time, then they will avoid you. i.e. if you're merely switching company for the same role elsewhere, fine, but career changing or graduate then they may avoid. What agencies do is do the cold calling for you, and with graduates or career changers they cannot be sure when you will land a job. The targets they have are pretty tight, so career changers and graduates don't fit into their business model.
I'm not criticising agencies or moaning about them, or even saying you're not good enough, just pointing some facts out about how their business works. Unless you're in the right position and/or the market is back to the 2004-07 boom then the strategy of "try as many agencies as possible" probably won't pay off.
Better routes to market - grad scheme as a "general analyst", then move into quant finance, as grad schemes aren't as tough to get into.
Or better still look at networking options. That's essentially what agencies do, except you could go direct it instead of them doing it for you. Maybe cold call through a list of firms - if you've done a market research or sales role ringing businesses up (a typical college job) this is an option as you will feel comfortable, but you will have to work on a script with someone that knows the market. Also from my own experience in market research, where back in the day I used to ring businesses up to do surveys, banks were by amongst the toughest firms in terms of getting through to the right people, only security companies or large multinationals like HQ of big brands like Heineken were as tough (I remember that one because I got the FD in Heineken Ireland to do a 20 minute survey once, was chuffed with that).
The way to do it is to find some informal networking that pays dividends. I can't say what this will be, but usually something that isn't marketed as a "networking event", like a coding meetup, might work better. I freelance as a data professional and 3 clients are all through Meetup and a socialising group. Neither are "networking" groups per se. One is a coding meetup, where the client saw me in action and could tell from talking to me that I understand how business works (which a lot of data scientists don't) and that I could bang out a data model for his business pretty fast as I knew how to take on board the querks of how his sales work. He also hires newbies if they seem to progress with our projects. Granted, I have found that as a business owner clients come to me (to an extent) and getting a role quant finance might be a bit harder, but a lot of business people come to the Meetup group looking for various professionals and it isn't inconceivable that someone to land a quant role through people they meet there. It's not 1980s/1990s unfortunately, bit more involved than banging out application after application.
