No, it tended to be extraordinarily effective. At it's peak, it was able to break German defenses pretty much by itself. The biggest problem was there tended to be quite a difference in the quality of the non-divisional and divisional artillery, in that the former received all the key gizmos and personnel for flexible fires while the latter didn't.
I did not meant to belittle the achievements of Soviet artillery, but rather the fact, that it was not qualitatively effectively due to large wastage of resources due to poor location ability and tendency to rather spend shells rather to norm than group them for maximum effectiveness. Also, the lack of flexibility on all levels was true. When making an attack against reconnoitred defense position the Soviet artillery was an unstoppable beast working in high, although not in perfect, efficiency.
IOTL from 1939-42 it was a larger factor in fire support than artillery, which had a hard time keeping up with the advance. That's not to say tube artillery didn't play A role prior to mounting it on old tank chassis, but it was not supporting the cutting edge of the advance unless it bogged down, because it largely lagged to the rear, as it couldn't set up fast enough and generally air support was trying to fly on standbye or ahead of spearheads to blast opposition on demand or in anticipation of demand. As fire support procedures improved, as did mobility of artillery, then it could do much more in support of mobile units on the attack than it had previous been able to do. Tanks generally were relying on maneuver and their own direct fire to attack surprised defenders or targets of opportunity.
Partially we're comparing apples and oranges, I think While well trained CAS units of WW II, such as Stuka units in 1940, were immensely powerful they had to be briefed and prepared if used en masse and could be used only against clearly distinguishable geographic targets, such as was the case in crossing the Meuse. Artillery was more of a precision instrument which could be deployed faster, if doctrine was developed enough. But of course bringing the amount of artillery power against clear target such as in case of crossing the Meuse in time would have been impossible.
Actually German artillery was just as flexible as the US methodology, the problem was the lack of ammo, motor transport/fuel, supply issues, etc. later in the war when they went up against US and British artillery in France and Italy. They consistently were more flexible than the Soviet model, but couldn't compete with the number of tubes and ammo, nor later on the supply ability to move up ammo. In their defense a primary reason for Soviet mass casualties was German artillery, mortars, and infantry guns. But that is attritional stuff that doesn't win the war.
Compared to Soviet yes, but to US, I doubt. In France since Napoleon and in Russia since god knows when the artillery has been said to be god of the battlefield.In German tradition it was infantry and later armor. Germany did not achieve the tactical flexibility of Western or Finnish armies in practice. Historically, for example from Finnish viewpoint Finnish officers had huge praise of various German military skills, such as armor and artillery use outside Finnish special circumstance, air force, intelligence etc. the artillery was constantly evaluated as bad and no doctrine was imported, while on numerous other arms, such as armor, infantry etc. various procedures were.
(When building Finnish army in 1920's and 1930's due to personalities Finland got it's infantry tradition from Germany and artillery traditions from Russia. It was a good occurrence, other way around it would have been a disaster.)