Ok. Russia can retreat back to its old borders then and wait until its reservists come in.
Territory is useless after all, right? Just let them Ukrainians to enjoy this gift then, I am sure Russia wouldn't mind
Russia's chosen strategy is to take things slowly and focus on getting a better loss ratio. But of course, Russia is not the only one who gets a vote on how the war goes. Ukraine is proactive and seems to have applied a 21st century version of PVA tactics.
Russia's bet is likely to wait until the weather gets colder. It worked for the Americans against China in Korea. The situation was even more grim for them back then, with a huge retreat and terrible loss ratios. US army made a comeback, dealing heavy casualties to the volunteer forces once winter hit, because with winter equipment, it is impossible for soldiers to survive with light packing on their own, so Chinese forces had to engage in direct artillery duels and clump up. In the end, the damage US did was not enough to cause anything more than a ceasefire, but US "made up" for their deaths during the retreat and then a few tens of thousands more.
Talking about "Russian territory" up until today around 13:00, the claimed areas were not Russian yet. With the Duma approving the proposals today, it is from now that the timeline for Russia to start reinforcing "its territory" begins. Of course, Russia has already called in more troops well in advance of the annexation, because it takes time to equip them.
Losing a few towns to Ukraine was probably not in Russian calculations, at least not main calculations. It puts Russia on an increased timer.