They can work, especially for a niche educational page, but I’d treat caption length as a packaging decision rather than a ranking hack.
A useful structure is:
- First line: name the exact outcome/problem (this is what people see before “more”)
- 2–4 short steps, one idea per line
- One concrete example or common mistake
- A specific CTA like “save this checklist” or a question that invites an actual answer
The bigger risk isn’t length — it’s making the caption repeat the visual. Let the post deliver the headline/demo, then use the caption for the detail someone would want to save.
I’d test it in matched pairs for a few weeks: same topic type and format, but alternate short vs. detailed captions. Compare saves, shares, profile visits and follows per reach, not just likes. For a how-to page, a longer caption that gets fewer likes but more saves/follows is probably the winner.