I totally disagree with you.
In my opinion, things would have been worse for Russia in the long run, if they ended the war too soon.
People like you are so used to globalized liberal market economy that you think it is the only way to organize a country's economy. You think GDP means everything. I, frankly, don't think so.
Because structurally speaking, Russia do NOT have any overall shortages in its own economy: it has way more land per capital than world nations average, it has no shortage of water, no shortage of food, no shortage of infrastructure, no shortage of technology. In fact, it is globalism and Russia's relatively open market to the world, as well as Russia lack of governmental strategic planning and subsidizing of industries that has been breaking down and eroding the once humongous and robust Soviet industries, letting it fall victim from unfair competition from the the globalized West and econ partners of the West (China). Because we in the West believe in globalized liberal market economy as a religion, we simply take the whole "slow dying of the Soviet-era Industry" as something Darwinian and natural, and even righteous.
But I don't believe that is the case. Russia is NOT like China, where shortage of food and energy and water and land will restrain China ability to act more independently from global dynamics. Russia can really afford to be closed off to the West, and the huge need for Russia energy and potentially military and other high tech, from India and China, will put it in a pretty good place in the long run.
In fact, the longer this war drags out, the worse the Russia economy will look like from the outside, but it will also force Russia to re-form its economic structure. And the West will find another "Soviet-Like" planned-economy rising in Russia. The West can laugh at this now. But if people believe the US can be an isolationist/anti-globalism great power, so can Russia.
If this war is short, the Russian will still entertain the fantasy of going back the way things were before, instead of take the chance to do things their own way. Historically speaking, that's how sanctions works: it is only to shock and awe and scare the other side to capitulate, if they don't, it would be utter failure.