> Instead of 2 devs working for 2 months each on their own project, put them together on the first project for a month, then on the other project for the second month (simplified example, of course).
We did try this and it sounds good in theory but as the old saying goes 'two women can't have a baby in 4.5 months'.
In my experience (in this particular team and org) it would've simply been better to invest some time into documentation and suffer a short drop in productivity on a project when owners left.