I don't really have a huge problem with someone playing when it's convenient. It's not as if there are dozens of participants waiting around these days to make the first contribution.
However, I do have an issue with lazy squares, and I have to say MRM, I'm trying to work with your recent A3 piece and it's totally uninspiring. From a technical level the top edge is much brighter than the rest of the image making it next to impossible to blend with. (See Below at 200%).
To me, half the fun is seeing how people will work off your edges, but if you're not thinking of how that might play out, that kinda sucks.