I play solo and I don't have a habit of leaving my game running while I'm AFK. Early research time requirements of 1, 4, and even 8 hours are certainly reasonable, but the higher tier research period requirements of 16 and 32 hours are simply out of reach for me.

Those are intentionally difficult to achieve, research is not meant to be maxed out in most games.
However, we're thinking about some ways you can get it progress a little bit during offline sessions too.