Mount it where it’s comfortable to use or you will stop using it. I agree with not putting it in a corner, but other than that, I don’t think it’s that critical unless you have a very large system played at loud volumes.
Advice for mounting a TT shelf on a wall
For more than one reason, I have decided to place my TT on a wall shelf. Now it occurred to me that there may be preferable places on the wall for the shelf to be mounted. Taking into account standing waves, electrical interference (hum), and even height, I suppose that one location is preferable to another.
Also, this is a very heavy duty shelf, and there may be additional considerations just because of this. No doubt, I will locate wall studs for mounting. What considerations come to mind for this?