30-45 mins avg on HN in evenings, or while waiting for something, or in-between tasks... I enjoy it and it keeps me current with the industry chatter. Sometimes I find cool stuff that inspires me to dig deeper.
I'm satisfied and don't beat myself up about it as I'm pretty busy and need downtime. So I don't feel the need to optimize much. Oh I do use Google Keep to save articles or items of interest so I can dig them out later if I have time to hack around with stuff.
... I have 2 young kids so hobby time is rare right now. It's increasing with time though :)