Perhaps the most important lesson for Putin is the realization that he cannot rely on the military’s assessments of its readiness, forcing him to take a more direct role in overseeing strategic operations. Ultimately, the combination of strategic lessons and a battle-hardened force will make Russia more lethal on future battlefields.
Even more, if they’re expected to engage in another sustained campaign, who’s going to be fighting it? They can barely keep their conscription pipeline full now. Who’s going to sign up to sacrifice themselves in Meat Grinder round 2?