It should be noted that Germany didn't put its economy on to a war footing until 1942. If it had done that in 1939 things might have turned out a bit different.
The German economy was on a war footing in 1939, but for the war Hitler planned, not what happened. German plans were for a series of short, sharp, victorious wars, with rebuilding of the armed forces in between. That was largely because the economy couldn't support continuous all-out war until there had been conquests to loot. 1942 was when the Germans tried to adjust their economy to fit the new reality, using the territories they'd conquered. Much of the increases in production weren't achievable earlier. The resources were not to hand.
Many of the biggest weaknesses, such as the reliance on horse-drawn transport, were a consequence of the underlying economy not being able to provide enough motorised transport, however it was organised. The resources weren't there. A fully motorised army couldn't be fuelled.
Resources had to be reallocated to domestic freight transport in 1940-41 because the railways were on the brink of collapse from lack of investment (it had gone to arms production) & inland waterways were short of barges partly for the same reason & partly because of losses in the build-up for Sealion (thanks, RAF). There were physical limits, & the war economy kept running up against them. It got round manpower shortages by pulling in millions of workers from occupied territories, but at the cost of lower quality, & that wasn't possible until there had been conquests. It couldn't get round some others, such as oil.
Increasing production pre-war was limited by resources & imports. Paying for more imports needed exports to earn hard currency, but more exports meant less weapons production. Nevertheless, Germany was spending a very high proportion of national income on the armed forces, & squeezing consumption to pay for it.
