Here is some truth to this kind of missions. As far as I know, they were not performed like this in the real WW2, but the idea was definately floating around.
A good friend of mine flew for the RAF in WW2, from 1940 untill 1945. From 1944 he flew P51B's for 65 squadron. All the way from Normandy and deep into Germany. His later missions were daytime escorts of B-17's, - Berlin included.
It was a long and cold round trip, boring, uneventful most times, and in his opinion, not very effective.
His point was that the escorts alone could have hauled MORE than the B-17's, who flew out of England at the time. You have 2.000 lbs per fighter, 3 fighters per bomber, and 2 trips instead of one. That is 12.000 lbs per bomber, 6.000 if you take only 500 pndrs.
3 fighters have a crew of 3, and a total of 3 engines, 3 fighters and one bomber a crew of some 12-13 (?) and 7 engines. And the 3 fighters come and go much faster.
If getting engaged, well, then finally there would be a fight, since the Gerries avoided the fighters most of the time. And the exit part? Who's gonna catch you, and why try to catch a swarm of well toothed fighters.
You'd only need a couple of Mosquitos to pull this off he said. Drop on command, unless you want to dive bomb, which would also be suitable and solve the problems of ... clouds.
I think he had a valid point.