You never think you'll run out of 10 litres of paint. It turns out that you can use the stuff at quite a rate if you go round painting 3 rooms in two coats each. After the second coat of emulsion on my living room ceiling, it was clear I didn't have enough paint to put a second coat on my second bedroom. So, I set about the process of undercoating. This is a non-trivial task. As a result of the undercoating, the living room looks totally brilliant. I ended up working until around 11pm on it. I undercoated bay windows, skirting boards, doors - you name it, I undercoated it. I probably applied a litre of the stuff.
If the previous day hadn't given me painter's arm, today certainly did. I slept with much discomfort.
However, the bank holiday weekend had afforded me a lot of opportunity to progress the house and the effects are noticeable on every floor. Progress in 4 rooms, plus a little in the upstairs hall too. There's a lot to do to complete a room, but I feel like I've broken the inertia that has beset the house. This is good news.