IMO 1/3 or stacked . 50% is not good for that size tile and I do not think slate suits the formal herrinbone and not wrth the extra cost of install.If you look at the last pic at 50% you will see the lippage .I have slate look laminate in my MCM home and I love the look BTW

I like picture #3.

Stacked 1/3 overlap, but I don’t see your pic for that. I bought 36x6” porcelain tile and the instructions on each box say do not stack with 1/2 overlap because of the lippage issue. My tiles have a bit of bowing in the middle. It’s a known issue with the manufactured planks. Your tile is shorter, wider and natural stone. Ask your tile installer. Get a certified tile installer if you don’t do it yourself. They have to have a lot of experience before they get certified. Otherwise research this issue on google before you decide.

I’m not sure if this would apply to herringbone with your tile, but it might if it overlaps 1/2 tile.

I will add that I installed 12x24 marble tile that was 3/8” thick, completely flat and smooth with a mesh on the back, cut down and overlapped 1/2 tile. It was only a fireplace hearth and I did not have lippage issues that I noticed, but I spent a lot of time on it to make sure it was level. So lippage may not be an issue with your tile. Ask a certified tile installer who has worked with this stone before.

1/3

1/3. It prevents lippage.

I really dislike the odd stair step effect that you get with 1/3. To me it always seems like it was supposed to be stacked or 1/2 and a drunk person laid them at 1/3!!

I would keep it simple and go with straight/stacked.

I hate the 1/3rd off set also. The herringbone to me looks the best