Back in WWII, both sides roll out newer and better weapons very quickly. During the course of a few years back then, many weapons rose and fell because of better weapons on the other side was designed to counter them. It didn't take long for something to counter something else. Now, each newer version of tanks, jets, helicopters, etc. take forever in the testing stage. Sometimes it take a decade or two before something can be finally in production. Once something is in the service, they also stay there for 3~4 decades before being phased out. Is the much slower pace of development of newer weapons a result of no hurry in peace time? Or is it because the modern weapon systems are too complex to be rushed? Or was it because the WWII weapons had to be rushed out for emergency before all the problems are fixed?