When we walk in a normal fashion we make alternating footsteps. So when we make stepping stones they should be perfectly alternating as well. You can decide to place one kind of stone or you can place slabs of natural stone of which no one looks alike. To make an infinite amount of blocks would be a lot of work, by rotating them it looks like you used more different blocks than you actually did.
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Tags: alternating, random, foot, steps, group