Horizontal wall mural panels?

I've done it a couple times, nothing huge though. Anything over 12 feet wide I would get a second person. It's a little tricky keeping straight but not terribly bad, it helps if you can cut the backing in the center to make a hinge so you can keep rolling it as you go on either side to help keep it straight.

Also depends on your material.

 

I have done it several times, no problems. I'd recommend using a laser line and second the center hinge method. Obviously you're going to want to overlap top over bottom.

 

We have a particular customer who insists that one particular item we print for them always be done with horizontal seams. It's really a matter of preference (though I personally prefer vertical seams in most cases).

 

For interior graphics vertical seams usually works best. Vertical seams are less discernible and more "logical" to the eye (we are accustomed to seeing vertical seams in wallpaper and paneling, etc.).

Horizontal seams work fine too, but it is false logic to think that the fewer seams the better. If the client is insisting on horizontal seams on very long runs (say, over 10'), the the odds of the vinyl distorting (solvent inks, heating, etc.) increase and lining things up becomes a challenge. If there is no continuous color gradients or text to line up, it may not matter so much.