To be clear - I didn't mean that the two _roles_ are mutually exclusive. The opposite - I think that definitely, there are common quality required between software engineering and technical writing.

What I meant is that in real world, due to times constraints, they are. As a sibling poster commented, working as a hobby ends up being a work in itself, so doing both things ends up being, effectively, overtime.

And as a consequence, all the general considerations about overtime apply.