Quick look at the hive today: they're flying like crazy, lots of activity, so that's good to see.
I've been piling in the 2:1 over the last couple of weeks but today, there was still a few millimetres left in the contact feeder, four days after the last top-up, compared to the last couple of weeks when they've been taking down two litres every 2-3 days.
So although there was still a lot of activity around the feeder, I'm wondering if they're slowing down because the hive is full. Anyway, I shall make another 5-litre batch, just in case, and if they don't need it, it'll keep....