And, if the Russians were desperate, they'd be moving a lot faster than they are rather than grinding the Ukrainian army into dust.
The Russians cannot more quickly, else they would.
It is extremely inefficient to grind armies to dust.
Much better to break through and maneuver them into “pockets”, or even just get then to flee and destroy them on the road - ex. “the road of death” ca 1991.
Even the WWII Soviets knew that, and did that.
https://en.wikipedia.org/wiki/Operation_Bagration
If thats not the point of these attacks, its because the Russian military is unable to do that. That leaves them with sub-optimal, inefficient methods.