As you all probably know by now, backgrounds are like pizza crust for me* - I'll prefer to attack them at the start of the meal so I can round the experience out with nothing but a delicious and flavourful cheese and tomato filled run to the finish. I don't skip them - they're an essential part of the meal and I intend to clean my plate/honour my commit to create fully rounded paintings and improve my overall skill set as a result.
So for this one it felt best to paint up from greyscale and then layer in colour afterwards. Sometimes it seems more efficient to keep the figures in the painting and only paint the bits of background you can actually see, but as this one features a lot of transparency it felt easiest to switch everything off and go for the whole background in one go.
I may I'll tweak and embellish the background as I go further, but this feels about the right place to get it to - there's always the risk that the background and its details can overwhelm the foreground so pulling the ejector seat right now and addressing the rest of the painting feels about right.
*Completely unrelated pizza factoid - I actually ditched all carbs and grains about 7 years ago and now make pizza base at home with only cheese and eggs, so I no longer have that issue at all - it's just cheesy, meaty, protein packed goodness all the way and I've got the best abs I've had in my life. Unfortunately there aren't any such shortcuts/efficiencies in background painting - but hopefully the metaphor worked to explain why I tend to work back-to-front.