Very true. There is no simple/guaranteed way of 'guessing' when it will be cheaper than Go overnight. At times, over the past 9 months, it has been cheaper to top up in the afternoon than in the early hours of the morning. The other great unknown is what effect CV will have on the generation and demand profiles. Agile isn't a sit back and forget tariff - and the recent winds have been unusual.A windy night doesn't always mean cheap prices. Tomorrow evening is higher than this evening so I'm filling tonight and expecting tomorrow night to be more expensive.
It doesn't always work out that way, but it mostly has over the last month or so.