Hi Adrian, it’s an interesting question and I think it depends on a lot of elements. Are you in bright daylight or in a dark studio? Are you parallel to the camera or behind it? in General I prefer it to have it a little ”open”, meaning that I can easily switch my sight from the monitor to the actual scene and see if the actor and/or the camera/dolly/steady are hitting their marks correctly and so on. It is different when I’m in a situation where I cannot have a clear line of sight, then I prefer to have it totally straight in a position where I can watch it comfortably. It also depends on what monitor you are using, given that on some monitors only allow to see the focus in a very reduced angle, in which case I prefer to use the monitor just as a frame reference and pull using marks and eye guessing.

hope it helped!