JV, at Qantas we call out fuel drains on our A330s at each "7 day" check. We find the same problems you have encountered- fuel temp too low, water still "frozen", frozen drain valves. We recommend to carry out the drain as long as possible after arrival, (at least 5 hours) but failing that we sometimes refuel with "warmer" fuel and then do the water drains.
I also find that too much water in the tank can lead to fluctuating/degraded fuel qty indications. I don't think escalating the water drain past the 7 days would be appropriate.