I think the biggest challenge on any mission was to create and maintain an acceptable Squadron Formation. The challenge began with Squadron Assembly shortly after take off. This was especially tough in weather conditions and in darkness. A level of formation was maintained for the entire mission so the pilots put in a long days work.
The Squadron Lead Pilot was the key. Every movement he made had to be slow and deliberate to enable all others to follow. The formation became very tight when bandits were reported in the area. The same was true on the bomb run. A tight formation gave the Squadron maximum fire power and prevented the bandits from passing through the formation. On the bomb run it enabled a compact bomb strike foot print on the target. A big challenge for the pilots was to stay in the formation through the turn after bombs away. It was a unit turn not a single aircraft maneuver.
The talent of the Lead Pilots I flew with was unbelievable. They were under pressure for the entire mission.
Yes, my 303rdbg did. I was not on the mission but saw the .50 cal. holes in the skin of the aircraft following return to Base. They were jumped South of Hamburg by a number of ME-262 aircraft when returning from a mission.