This is exactly what I do as well both in my current and previous jobs. I've never advertised exactly how much time I spend on courses but did ask (and get) per

This is exactly what I do as well both in my current and previous jobs. I've never advertised exactly how much time I spend on courses but did ask (and get) permission to spend some of my time on personal development. Sometimes I would take Coursera/EdX courses and sometimes just read through books and do some exercises, generally around analytics/computer architecture/numerical methods. I've generally always been able to apply some of the things I learned somewhere in my job, leading to happy colleagues because I injected new solutions and insights. I feel like as long as you prioritize your work well and you make sure to finish enough high-value tasks employers tend to not care too much about whether you actually fill up 40 hours with these tasks. Being able to use any left over time for myself also incentivizes me to stay productive so I'm pretty happy with this system.