Their efficacy depends on your learning style. I personally get bored pretty easily with lecture-style learning, even through an online course. I need more experiential learning. So with cybersecurity I’m picking it up through:

- Study guides and practice exams for certificates (that I may or may not get). This is probably the critical thing I do because it sets a track of what kind of material I should be focusing on for the subseqent learning tools.

- Anki/spaced-repetition to remember things like acronyms

- Quick YouTube talks (specifically those not in a webinar format; usually bad production quality and a lot of padding not related to the topic)

- Games to put theory into practice (CTFs, bug bounties, video games that are very abstracted from real hacking but still require exercising logic)

- Podcasts that look at the industry from different perspectives. Currently listen to CyberWork, which has a lot of fluff but I offset that with Darknet Diaries which does a great job of storytelling.

- Trying to explain these concepts in layman's terms to others