gap

How often has an aircraft been retired before its successor was ready, creating a capability gap? And how often has a force (Air Force, Navy, etc) gotten away with the gap vs suffering in combat for it?

Hello, everyone. I'm working on a Revell 1/72 Me 262. I've attached and glued on a resin, replacement engine to the wing. However, after attaching the engine, I noticed there was a long gap that runs between the side of the engine and the kit part. I filled this gap with grey tamiya putty...