That works in theory. Again, I'm not an ATC, but might be better to have reasonable length workdays (maybe two hours is a reasonable shift though) and more time off between workdays. Similar to shift work in hospitals, where more hand offs means more opportunities to fail to hand off successfully. But I suspect it may be easier to hand off an airplane than to hand off an ICU patient.

I know nothing about this field, but if the main claim is personnel shortages, it seems like reducing your workforces hours by 75% would not be optimal.

Is the personnel shortage is because most people can't handle 8 hour shifts, then it's plausible that you'd have more than 4 times as many people that can handle 2 hour shifts

If 1 in 100k can handle 8 hours, and 1 in 10k can handle 2 hours, then the solution is to employ 4 times as many people for 2 hours.