When you choose to build a wall, you're specifying in what direction you want to build in. But why do we have to keep doing it over and over if we want to build in the same direction multiple times? My suggestion will remove the monotonous task of wall building and make it more user-friendly.
In the picture you will see me starting to build a wall segment; however you will notice a new button. Pushing this button will tell the client you want to build another wall segment and update the material requirement accordingly (you will still have the single construction sign.) Depending on how many times you want to do this, when you right click the the construction sign it will display a visual aid to show you how far the wall will go (I used little red dots to illustrate my point.)
When you're ready, you click build as you would normally and then wait for the construction to complete.
Edit: There will be no need to walk along with the wall's construction because it will only build the entire wall when you've finished building. And of course this system will need to be fine-tuned to prevent griefing with it, like building walls through objects and other walls, so there should be a check each time you add a wall segment to the queue on whether or not something's blocking the path to prevent the wall from being built.
