At least in my experience, there’s nothing about research that requires engaging with it in “hours-long continuous threads”; what you do e.g. in a single two-hour session can be done in four half-hour sessions, on four successive days. I think the limiting factor is rather having sufficiently many concurrent (and non-time-sensitive) research projects that you can fill an entire workday with 30-minute slots each allocated to a different project. That may be challenging for some researchers, but it’s really not a problem if you write encyclopedias for a living.
At least in my experience, there’s nothing about research that requires engaging with it in “hours-long continuous threads”; what you do e.g. in a single two-hour session can be done in four half-hour sessions, on four successive days. I think the limiting factor is rather having sufficiently many concurrent (and non-time-sensitive) research projects that you can fill an entire workday with 30-minute slots each allocated to a different project. That may be challenging for some researchers, but it’s really not a problem if you write encyclopedias for a living.