German technology in ww2 is commonly seen as this rapid sweep of insane technological achievements and sometimes disastrous failures which caused the state precious resources. Why didn't nazi german stick to what was working and funnel this money mainly into the war effort and not into these new designs which were unproven?
I'm unaware of any super impressive technological achievements by the Nazis. What are you referring to?
For one it wasnt just Germany. EVERY nation was actively attempting to develop new and more effective weapons and systems.
So if you weren't you would fall behind and lose badly. A good example is that Japan trained and their Navy became expert at night fighting. To combat this the US did some training but also heavily invested in Radar controls for their guns to an extent unseen before. Thus by 1943 the USN was able to dominate surface engagements with accurate fire.