Without neutral AR's, I 'm a big fan of standing off the goal line.
There's no such thing as perfect position. It's a matter of weighing up what is more likely to happen, what's more significant, and how much Position A enhances your ability to see one thing but compromises on another, versus position B.
The most important thing that can happen from a corner is a goal. That's a close ball in/out situation in the goal. It doesn't happen often, but there's only one position on the field that allows you to see it.
Ball going out on the way in is pretty important too, because missing that can lead to a goal or a penalty kick that shouldn't have been awarded. That's the problem with the 'off goal line' position - you do need to glance at the incoming ball while monitoring players. A quick glance shouldn't compromise too much.
It's probably the best position to spot deliberate handling too, especially on the goal line.
Other potential compromises of this position:
- your angle of view isn't as wide - I've never felt like this is a problem though. You can still see all the players in the box when you're looking back into them. I don't think I've ever had anything occur out of my field of view. Even the pushing and shoving behind the drop zone is still in my field of vision. I don't think happening out of your field of view is the issue, so I don't think this is a problem
- The angle means you may miss some contact. To be honest I also don't think this is a compromise - for every incident this gives you a worse view of, it gives you a better view of another one. I've caught plenty of holding/pushing in the back from players running in. That's probably the hardest one to see from this view, but I don't think it compromises that too much. Conversely, it gives you a great view of the pushing and shoving immediately around the keeper - and when players are falling over on the goal line and scrambling, your view is perfect, as opposed to trying to look through a crowd
- You're behind play if there's a counterattack. Yes, but these scenarios end 1 of 4 ways. 1) The ball is intercepted and goes out. 2) The ball is held up near the halfway line. 3) There's a foul, probably around the halfway line. This one is usually fairly clear and you can spot from anywhere on the pitch. 4) Ball goes all the way to the other goal and there's a tackle in the box. Worst case scenario, extremely unlikely and you're still pretty likely to be able to see what happens there. (see what I was saying earlier? Your position may be compromised for this a little, but you're not left completely incapable of the decision)
- I think the worst thing that can happen is the corner goes long to the far side, and play gets held up there. That's about the only scenario where your vision is pretty heavily compromised. So, if corners keep being long, you may not want to stand off the goal line on the short side. It's hard because you want to try running out but not through the centre of goals. I think I've ended up running behind the goals on low-level games at some point!!!
- Offside - I think this position is easier for some offside infringements, harder for others.
For me, considering what I said before about the most significant decision and where the pros/cons lie, I feel like standing off the goal line is almost always the best solution without a neutral AR. Basically, this is a detailed consideration of WHERE is play going to go? WHERE can I go to get the best view of it? GO there!
By all means, try different positions. As an assessor I might suggest that referees try this position but not tell them to.
And some games I've mixed it up if corners tend to go a certain way.
And of course, if it looks like the corner is going to be taken quickly - don't get in the way by running to the goal line!!!
Your issue, as others have said, may be too much ball watching. Glance between players and ball. When you can see the kick is being taken, glance back to the players. Hear the thumb, glance at the ball. Is it travelling down the line? Then you have a problem - which one do you watch? Maybe keep your head on a swivel. If you know it's staying in, forget the ball, watch the players.
With a NAR I'll position myself somewhere between the penalty arc and the corner of the PA, opposite side to the AR (to maintain the principle of a triangle of you-ball-AR). Move around, but there's no need to be off the goal line here, not unless you think there's a particular reason for you to be that close.