Also, a precise approach is required. What you want to do is first run along the TG group in perfect parallel, and then when you pass the TG, turn towards the TG in exact 90 degrees. When at the moment you do so, the target ship must be seen at the 90 degrees position marked in the upper picture.
If the target ship is behind that position, you turned towards the ship too late, so you have to throttle down. If the target ship is in front of the position, you turned towards the ship too early and have to throttle up a bit.
So in my view,
HO runs: easy to aim, and easy to survive.. but with slightest movement the ships can evade torpedos easily, as much as it is easy to aim it is also easy to miss if the aim is wrong, it takes a long time to set up
90 degrees runs: no pros, only cons. takes long to set up, requires precision, low survivability, hard to aim, hard to hit...
45 degrees runs: average difficulty in aiming, average survival rate, easy to set up runs, high possibility of hitting ships, and ships cannot evade torpedos easily.