It's most certainly worth the time and effort.
A well organized box of bombers is a tough nut to crack. During the last FSO
But the MA is not FSO.
I would say less than one bomber mission in five that I've flown has faced significant fighter opposition before reaching the vicinity of the target. And as has been pointed out, once you're near the target the formation has to break up anyway to line up on different targets, something rarely done by American strategic bombers in the war. After the drop I just want to land as soon as possible, and having a fighter or two follow along to play just gives me something to do during an otherwise boring return flight.
That doesn't mean we don't stick pretty close together flying to the target, but that's not the same as forming and maintaining a box, and the goal is different (hitting the target at the same time as opposed to defensive firepower).
Anyway Lancs didn't fly combat boxes, they flew in a bomber stream - of course that was at night, but daylight raids in the MA often get less fighter opposition than night raids inthe RL war.