That map is worth linking from part 1:
The large numerical advantage, and potential replenishments from deep storage (> 17k old artillery, 4k self propelled, 12k towed) means that successful slow fighting retreat with much greater attrition of Russian forces than of Ukrainian does not prevent Russia continuing the war after having occupied whole Donbas with aim of encircling major cities and bombarding to compel a ceasefire while holding territory that landlocks Ukraine.