Back at Yavin they have more fighters than experienced pilots and Luke is experienced with similar craft and they have nothing to lose.

It makes human sense.

Similar things happened in both world wars.

The Death Star is the size of a small moon and has exterior as well as interior spaces.

Ben wanders around because he uses the Force to distract people but the others stay in one room, briefly wander around in disguise and then run after being detected.

It makes sense.

Nobody is made an instant general in ESB.

It doesn't make sense in ROTJ and saying, "but it's fun" doesn't cut it with this viewer. The first two films proved films can be fun and also make sense.