They certainly allow you to learn. I'm able to tell my manager I'll spend a sprint(s) tinkering with build performance or reading stuff that's relevant to our work (i.e. the Goog SRE book).
You learn by challenging yourself to build things and solve real problems, and doing something meaningful like this requires a flat structure and business exposure.
Tinkering with a build system and reading some corporate groupthink? That's not learning, sorry.
