So that doesn't actually make my claims wrong though. I actually did do a few quotes, STAVKA and Semyon Timoshenko.
The Third Reich had extreme fuel problems since 1941. In addition a severe loss of equipment as a result of Operation Typhoon also resulted on a reliance of pack horses. German supplies were mostly pulled up to the front by horses, especially on a local level where rail was impractical. This prevented panzer units from carrying out rapid advances since they had to wait for their supplies to be pulled up. They generally didn't have much fuel after 1942 to carry out many maneuvers. The Germans managed to acquire Italian oil reserves in 1943 after Italy was knocked out of the war. Other than that they relied on coal liquefaction which was not in large quantities and not efficient, very low octane. The Allies crippled German oil by destroying synthetic oil production facilities, coal facilities and carrying out bombardments of Romanian and Hungarian oil facilities. By 1944 the Allies were pushing on Alsace which was also an area of German oil and coal production. In general the Germans actually reduced mechanized equipment because they didn't have enough oil to supply them and so kept the oil for specific mechanized units and for panzers and airplanes.
Nope. STAVKA themselves emphasized the desire to make German units carry out costly maneuvers from 1942-1944. They knew that flexible defense wasn't feasible because the Germans would simply run out of oil and be forced to halt, and then wait for resupply. Something which the German leadership also pointed out to these generals.
"... we have to do all we can to make Germany increase her oil consumption and to keep the German armies out of the Caucasus" - Semyon Timoshenko, during Operation Typhoon
Many of them disagreed with the Ardennes offensive in 1944 but by that point who even cares. The war was practically over. That they were correct here doesn't really matter, a broken clock can be right at least once.
But for Kursk that is not the case. Manstein was for the Kursk offensive, he even helped to plan it. Kurt Zeitzler planned Operation Citadel and he was by all means a competent person.
Guderian obviously doesn't understand the strategic situation. He is arguing for decisive battles and wars of annihilation, which isn't possible by 1943, let alone in Russia. Obviously Hitler's strategy was to secure Kursk and straighten the front line intended to absorb a Soviet offensive. The value itself is not in Kursk but rather in the encirclement of the 500,000 Soviet troops, which if lost would significantly hurt Stalin's manpower. Incidentally Stalin was also organizing battalions of women and children in 1943. The reason Operation Citadel failed was because the Soviets had in depth knowledge of these plans which they discovered through their extensive spy network and British code breaking.
Telling me about sources... you're using Wikipedia as a source and their source is Guderian's memoirs.
The luck in the first part of the war? The Germans intentionally increased rearmament from 1938 onward. It isn't luck if you do it on purpose. If they are doing it on purpose they obviously realized that the particular thing was a factor.