New to CS - how do you divvy up your clients and what's your frequency of connecting with them?

We are relatively new to customer success - I'm a CSM and I have a whopping 749 accounts I handle.  Needless to say, we are constantly under water.  How do you all divide up your clients for your CSMs?  We are a fintech company.  Currently, the only CSM in our org that has a firm handle on all her clients is our London based colleague, who only has 50 or so clients and she knows ALL of them.  Help!  What's your contact frequency?  By phone? By email? In person?  Do you send chockes.gift baskets/hoodies/t shirts?  

We need a new plan from our current one which is call every client every quarter.  I want to present our managing director lots of options! 
Thanks!