In reply to Andy Hardy:
The problems with auto belay are firstly that you can't dog the moves. You not going to do anything near your limit if you can't dog it. A second problem is that auto belay routes cannot be very steep because of the risk of swinging outwards if you fall low down. Vertical routes only train in a very limited way - for instance you won't be using your core as much as on a steep route. A third problem is whether you can even find something at your limit. There's only ever a very limited supply routes at most walls and most will be either too hard or too easy. Low level traversing on a board with plenty of holds, if there's not a pre-existing route at the right grade, you can design your own choosing whatever holds you like.
I agree with you that up routes will be more specific. Personally I prefer straight up lead routes when I can get to a wall with a partner. But, for the solo climber especially, I think the accessibility of low level traverses have a unique place and purpose.
Post edited at 09:32