Multitask repetitive or time consuming tasks only. When I was in college I worked for a mom and pop type PC repair store.

Doing PC re-imaging, I set up 6 stations and would kick off one refresh and while it was running, start up the next one and so on. Using disks to install took ages, so I figured out how to make bootable USB sticks, so I would have all 6 or occasionally more (by stealing bench seats) stations humming away while I was also doing part upgrades or builds on another station, only pausing to check up on progress.

That is ideal multitasking, where you need to pay a small amount of attention to one arduous group of tasks and the remainder of your time is free to focus on fine detail high mental demand tasks with ease.