There is a speculation that RU forces haven't been moving around for more than a month now. They just hold static defence, and push piecemeal attacks where they do, without new forces coming to plug holes left when they expire.
Avdiivka been the sole notable exception, and it might've been done by Russians exactly to insinuate that they can sustain more than two pushes at at time, and make Ukrainian HQ think twice about RU push being close to exhausted.
Donetsk hosts the biggest ball of Russian manpower on the front, and Russians only tried to activate forces staying there for a push just few times in this conflict before, and these pushes were always wound down, and recalled.