This is why i back butter every time and not the walls.
You should be able to tile to walls without doing this. There's a way to keep clean as you go, and you just need to clock it. back-buttering when not required is a lot of time wasted. And I don't think that's just my opinion. Try to get out of that habit mate. Checkout some tilers tiling walls on youtube and how quick they stick them on.
If you have a tile on the wall, your next tile should be pressed into the wall whilst touching the first one. Then you use (and I quote british standards I think when I say this) "a twisting and pressing action" to easy the tile onto the wall and into place, leaving the desired spacer gap.
What this does is cause the suction that normally causes oozing out of the grout joints to actually be sucked into the backing of the tile and out of the side your twisting it towards. So then you have to simply clean that side up, the bit not near a tile yet, with a sponge if required, and then copy the motion on the next.
You can even do this when you have a full row you're tiling on top of, and have the row you're currently tiling along on the wall. In this case, you place the new tile sitting on the last row, and touching the tile on the current row. And as you twist and press, you move the tile up and away from the tile on the current row to your desired spacer requirement.
Try it, it works.
😉 This is also meant to leave 80% coverage on the back of the tile, the minimum for walls, though in wet areas if my memory proves me right I think it's 100% (might be 80 - 100% - anybody confirm that?)
Another thing is this; if you back buter every tile and don't apply adhesive to the walls, you will end up using grout in the voids. Grout costs more per KG than Adhesive. Not wise.
