I recall, while I was still taking courses in grad school, it was like 2-3 hours in class/day, and maybe 2-3 hours in the coffeeshop or lab working on research, plus teaching/grading work. When I was done with courses, it was a little less intense, but still at least 3-4h/day
Now, to the extent I can even call myself an independent researcher with a straight face, I spend maybe 4-5 hours a week... like one afternoon. Something like 10-20% of grad school level. And that's on a good week. I see no line of sight to getting up to 20-30 hours.
I think all the talk of indie research/scholarship etc. are basically impossible if you're also earning a living doing something else. Ie you have to be retired-early and independently wealthy.
It's nice to see people trying to make various sorts of micro-grant programs happen, but I don't think they're funded at levels high enough to make meaningful indie research possible, in terms of freeing up time for later-life people with higher cost of living.
Even in my first year as a grad student, I made ~18k/yr, and in my last year as postdoc I think I made ~55k, and that was mostly as a single guy with very low cost of living and expectations...
I personally don't count my writing as research. If it goes straight from idea to writing, without intermediate steps like field work, coding, math, deep prep notes, or experiments, it's not research in my book. Going straight from reading to writing is more like criticism.
Structuring time for research is far harder than structuring material resources (equipment, lab bench) or space (properly sized/ventilated/lit area for the type of work). Research is a natural time monopoly. It wants to take over all your waking hours.
Natural monopoly in time is an interesting concept. Language learning is another example. The speed increases superlinearly with time fraction of immersion. That's why actually being immersed in the foreign language country all waking hours is the fastest.
My material resources state is basically complete. I have all the stuff I need except for a high-powered workstation (not a good time to be shopping for that). Spatially, my spare bedroom is a decent space, but not the best, it's about 12x12 feet, and ideally I'd like 3x that
But time-wise, I'm not able to arrange my time properly to make progress at the rate I want to. I need time for a) refreshing old subjects b) studying a few new relevant ones c) working on the research proper (I'm thinking here mainly of my rover project, though I have others)
If mixing in writing (non-research... blogging/newsletter) and consulting work weren't an issue, I'd arrange a grad school like schedule: study sessions, lab sessions etc. on a fixed calendar.
Context switching is brutal among the 3 activities and consulting cannot be batched or made asynchronous beyond a point. You ideally want pure research time in week-sized chunks. Basically impossible for me.