During the wars there is little time to develop new weapon systems, because they have to be rushed out into mass production to counter enemy threats. The quick cycle of weapons development left many bugs in the newly deployed weapons on the battlefield. A lot of problems were not noticed until they were in service, by then there were always already many units in combat. In WWII for example, from what I have heard even the most fearsome German tanks such as Tiger, Tiger II, Panther all had tons of problems when they were just fielded. Of course, the engineers were working as quick as they could to fix all the problems as soon as they are discovered. Not all problems could be fixed so quickly or even had a solution that fast. It took them, and problems had to be fixed one by one. The question is, when a solution is out for a specific bug, did they pull back all of the units from the battle for fixing? Or do they wait for more solutions are out for a bunch for bugs than do a large "patch" to fix a lot of them all together so they didn't have to recall all units every time for a small fix? Didn't the recall and bug fixing cause problems for the deployment?