yes, documentation would be great, but it's so hard to do properly (and basically unrewarding).
Sometimes there’s highly specific - reading the docs.
Sometimes it’s adjacent or wildly different technology/concepts.
Sometimes it’s thinking about a side project or making a toy piece of software to try something out, and the reading that goes into learning how to do that.
Equally just browsing HN and others.
I find there’s a lot of learning by osmosis that’s necessarily not measurable/quantifiable.
how much development experience do you have, and are you front/backend (or devops?)
As an expert in the system, I've done very little research - maybe 1 hour per day helping others troubleshoot. As a new guy in the system or as a security resource, I've done a lot - maybe 3 hours per day.
I am not sure if you'll find a good correlation to developer or area experience, at least by my personal experience people offload memorizing of stuff to Google search
But there are - as an aside - very real health benefits to having memorised the work. You're making less decisions (ie "what to google" and "is this useful"), which means you have way more willpower and energy for your daily life. Which is, of course, largely anecdotal but I think goes a long way to explaining traditional developer body types vs those in, say, finance.
(It's not like finance people are "less academic" than developers, for example).
They kind of dance around it, to be honest.