After its initial successes (or Russia's failures), it does appear that Ukraine is stuck in somewhat of a tactical/strategic rut in what remains of Luhansk. They seem to have thrown untold men and materiel into Severodonetsk for no apparent good reason, and its now being reported that the Russians have destroyed all of the river crossings at the Ukrainian's backs. As others have noted I cannot see much merit in attempting to match Russia's artillery superiority, round for round or rocket for rocket. Defense-in-depth seems much more appropriate in the circumstances; they've already demonstrated their ability to effectively fight this way.
Regarding western supplies, I do wonder if we are rationing them for some reason e.g. so as not to lose too much in the event of a local or wider collapse, or (more positively) to maintain a pretence that the Ukrainians did it mostly by themselves in the event of a Russian collapse or withdrawal? The 'rainy day' argument seems moot now, given Russia has effectively been nullified as a conventional threat.