At least it makes sense to keep the Russia on its toes. Keeps them from concentrating their soldiers elsewhere. And, maybe ZSU is lucky and will indeed gain another area like the Sudža corner. Then the Russia can bomb the towns there until they are destroyed, ZSU can retreat from them and get some intact towns to restart the process again. The Russia’s way is to bomb the city out of existence and then advance, but if the advance only means regaining the territory they already had before, sans its houses, it’s not a very efficient tactic :)

But of course that requires that ZSU can actually occupy those intact towns near the Ukrainian border. That’s easier said than done, but surely within realm of possible.