DDIA is a good book and I've read it at least 3 times, but there is no substitute for real world experience.
I also think a lot of system design material is oddly positioned in that it caters towards synthetic interview scenarios where you are designing mega scale systems but somehow are also the single person responsible for all of load balancing, CDNs, message queuing, databases etc ...
In the real world it doesn't really work for that way for product engineers.
It's good to know about that stuff but there's lots of other topics that would have higher ROI like learning how to plan and sequence work properly, how to reduce different kinds of risk during build and deploy, how to migrate complex, existing systems towards better architectures without disrupting the business, how to actually become someone who gets to design systems ...
The greatest trick the devil ever pulled is convincing people that shared hosting is preferable to dedicated, and then charging them way more money for it.