I made a pretty large hand drawn tile made up of hundreds of blocks, then I paste it over my entire map and mask out the edges, fill in gaps, so that the patterned effect is hidden whilst not having to draw hundreds of blocks for each map (though it still take a REALLY long time to do). Reason being is that the few times I've tried to do maps with walls I draw and draw and draw, and then sometimes when I zoom out I notice that there's big size variations in the blocks and a lack of consistency (really starts messing with your mind drawing them over and over ). I tried to come up with an easier method and that was the result, which I'm really happy with as I can rotate, flip, move the tile for each map so it always looks unique

Work smarter not harder!