You need to have a consistent layer of adhesive with lines of adhesive running in one direction only depending on the shape of the tiles. When placing the tiles on the grout you need to wiggle the tile in the direction of the channels of the grout so you collapse them ensuring no voids underneath the tiles.
Why didn’t you back butter the tiles for a better adhesion. I’m going to use your 1x2 method to get straight level tiles when I start tiling today. Great idea.
You dropped a lot of adhesive on the sheet at the beginning. I would have picked it up and used it or put it back in the bucket. Frugal I know but why waste it