I tend to do a lot of large format tiles so batons are important for me. I don't think I would have the confidence to leave them out of the equation at this stage. To set out I use a self levelling laser to mark the whole room then baton all walls. Even doing this method I still find that the tiles can be ever so slightly out when meeting up in the opposite corner. I'm not sure if it's a case of the level or the odd baton not being 100% straight. Then next time I tile I will try the method of tiling one wall at a time and then offering up the baton to the bottom of the tile.