Hi Shane, there are a couple ways that come to mind.
1 - if you add your company as a customer record in Gainsight, you could assign those type of CSM specific CTAs and use your company name as the assigned company. This would help you avoid proliferation of CTAs as you described.
2 - if you didn't want to go with option 1, you could pull in all the customers by CSM and then filter on the MAX value of ARR to give you the top dollar customer per CSM and then use that customer to trigger the CTA. In the description of the CTA, indicate that this is a notification CTA and the described action needs to be done for all of the customers in their portfolio.
Also - as Meenal mentioned, if you don't trigger a CTA per account, you'll have trouble tracking completion of the task. Asking them to log a Timeline entry would work in this scenario, but depending on the task, the Timeline entry might be more work for the CSM than just firing those 60+ CTAs and having them checkbox them as complete when the task is done.
VP of Customer Success at Forcepoint