Interesting. I've always kept it mixed. Can take a month or a bit more depending on tank needs. I never heat it just the WaveMakers to keep it circulated.My statement was regarding someone else and their AWC, not related to me. My AWC system is 500g container and takes 2 months before I make more. It only gets circulation, as a very large amount of water.It is also for a different tank.
I just did a 30g WC last night with water that has been sitting for over a month with no circulation until about 30 minutes before the water change. No issues what so ever and water tested as it should (I test sg, alk, and CA before doing a WC in tank and brute). During the time it was sitting, I had no cords in the brute either. Notch still there for when I cut it out previously.
With that said, I see no issue in storing water for a month or 2 in a brute once it is mixed up, then just mix and heat again when ready for it. I say mix on the second go, but it is more like circulate to allow it to heat up. Not really mixing as nothing separates in that time. At least for me.
So, there is not really a need for cords for some people. This is what everyone is trying to imply here.