I guess you will eventually the best approach to you. It is kind of personal.
Nonetheless, here is what works for me.
I prefer books when entering whole new areas of expertise. In this case, I need to make my own pace, going back and forth in the subject, pausing, taking notes etc. For example, once I had to set up a call center but had zero knowledge of VoIP et al. So I read The Asterisk Book and Getting Started with Elastix.
When I'm acquainted with the subject domain, I find video courses helpful. Since I can assimilate the topic easier, the pace of the course helps me avoiding boredom and procrastination. For example, some time ago we used JAX-RS in my workplace. I'm a well-seasoned Java developer so I burned by free trial of LinkedIn Learning with Alex Theedom's excellent JAX-RS Introduction.
I doesn't mean it will be the same with you, of course :)
A friend of mine could use that asterisk book! Thanks for linking it!
I wouldn't think of using that linked in learning trial ever, I look it up and check if there is anything that fits to my occasion.
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