Russia don't care if it takes 300,000 or 300,000,000 dead to get the job done as long as the job gets done, they've never been competent at war, they've just thrown huge numbers at it to win, this is their mentality, life is worth very little for them
A week is a bit of an over hype for NATO, look at Afghanistan, over a decade and they left the country pretty much how it started with Taliban in power
You cannot compare Ukraine and Afghanistan, its two totally different scenarios
Afghanistan was an insurgent/guerilla war against a population - a war like this can only be won with vastly overwhelming numbers to hold down the populace as Russia is finding out right now.
A conventional military war can be ended quite quickly because enemy combatants will surrender when it looks likely they may die or loose the will to fight and go home.
A more direct comparison would be the Iraq war, where NATO went in and cleaned out the Iraq military quickly. Even though Russia is obviously stronger, its the most recent conventional war NATO has been in.
Now for the numbers, NATO did a good job in Afghanistan, they just didn't have the numbers to supress the population. NATO suffered 3.5k deaths in Afghanistan, the Taliban and its friends suffered 56k deaths, thats a very good ratio.
The problem is even at its peak, NATO only had 130k troops inside Afghanistan and it kept dropping over time. Afghanistan is a population of 38 million, even if only half support the Taliban its 19 million people against you and you cannot suppress a population of 19 million with just 130k soldiers. With the new information we have, its been estimated China would need to send in 2 million soldiers to suppress Taiwan's 23 million population
With Ukraine you are not worrying about the population, its a conventional war and so it can theoretically be ended quickly - not in a week though, thats too optimistic.
And if Russia responded by getting kicked out of Ukraine by doing mass mobilization then it can take a lot longer - but from what we can see, it looks like mobilization while fighting in Ukraine is difficult for the Kremlin to achieve, but if the Kremlin can paint a picture of the enemy on russian soil then mobilization would be accepted by the population.