Oh for sure the initial tactic was a quick blitzkrieg and have Ukraine crumble in front of the might of the Russian forces which failed spectacularly, but their standard tactic they have reverted to is one of a long protracted conflict where they grind everything to dust in front of them.
I appreciate this conflict is far more intense than their recent wars, in terms of their losses and the economic sanctions far more severe, but the talk of them not being able to sustain things for longer than a week or two just seem to be a palatable message for our side. Though of course, I couldn't be happier if I turned out to be wrong in this instance!
It's clear that Russia has major logistic problems, major supply problems, and every day it's in Ukraine failing losing soldiers, tanks, planes, etc. and burning money on artillery shells the worse things get for it. Meanwhile, Ukraine's future looks bleaker as the damage to the country rises but it's chances of winning the conflict rise. Vast amounts of superior Western weapons are coming into the country, and while pounding the Eastern cities into dust may destroy resistance in those cities, it's hardening the resolve of Ukraine's main forces in the West and of their supporters outside the country.
This is a much tougher conflict than any Russia has faced since WWII, and it's worse placed to fight than it has ever been. The planned and structured economies of the Soviet era were garbage but at least they made stuff, after 30 years of banditry the country has been run into the ground and what manufacturing it has is almost totally dependent on Western machinery to function - machinery it can no longer get support, parts, and repairs for. Now, the war may end up helping the part of the economy that matters most to Putin, at least in the short term - as he and his core support all make their riches from Gas and Oil, and prices are going up - but to fight and win a protracted war they need a war economy capable of making at least vaguely modern weapons and they simply don't have it, and pivoting to it would require fundamental changes in how they have set things up. A setup that is in place to protect and preserve Putin's power and the power of his inner circle.
The numbers on paper point to the conclusion you've reached; but I think it's turned out to be a mirage. Underfunded, corrupt, and with anyone competent deliberately purged to stop it become a threat, Russia's army simply can't deliver. Putin's Russia is a paper bear.
But, you're right, maybe this is just cognitive bias on my part. It's the nicer narrative to believe, and while I try and read from a range of sources, it's not like I'm any kind of Russian or military expert, maybe I am just picking up on the ideas that are happier. But we've seen many times before that all the military might in the world can get bogged down and lost in military misadventures that grind to a halt. Particularly when the theatre of war is getting outside support: think the Soviet invasion of Afghanistan, or the US's wars in Korea and Vietnam. It doesn't seem to me that Russia being unable to win this war is something so extraordinary that it beats all expectation.