When India says it maintains/strives to maintain 3 weeks worth of ammo it is talking about a theoretical full-fledged intense swift war and not the kind you see between Russia and Ukraine. Just to give you an idea, by that definition even 1971 war is not considered a full-fledged one, even though India had a similar policy even back then. India barely depleted 10-20% of its stocks in 1971. It's a hypothetical case where all your forces are simultaneously fighting which will almost never happen in a real war and if it happens the war will definitely be short and swift for either side. Pakistan was surely not dumb to surrender in front of an enemy having barely a week's worth ammo left.
Also, don't see the comparison between Russia-Ukraine vs India-China scenario. The military firepower is nowhere as lopsided, India has poor border infra, true and we are yet to catch up but then Chinese jets would also have to take off from a much higher altitude. The nature of war would also be different, the reason Russia protracted this war is also because it wants a regime change, a swift short war leaves little room for that given the destruction it would cause, neither China nor India will have that objective in the war. More importantly unlike Ukraine, India does have the capacity to strike southern Chinese seaboard cities, if you do a tradeoff on the payload you can hit even deeper. China wouldn't have the luxury of one sided missile attacks that Russia has and that itself will shorten the war
If China could have done what Russia has done it would have surely not used nail fitted rods to beat up folks and upped the ante after Indian countermeasures in North bank of Pangong Tso or got into a now more than P
year long face off at Galwan, Xitler would have asked his men to blow IA up from there if he was confident. Also what's the fuss with Doklam? That they started making infra perpendicularly after India stopped them from moving forward towards the border? India itself uses this tactic when objected lol