Used to be every 10 hours here (looked like 9, because it would be at 9:50 by the time I did another attack and looked at it). Now it is consistently 20 hours, unless I wait much longer to use it. If there was 30 plus hours between the last time I used it and this time, the next time will be sooner. If I use it close to once a day, there is 19-20 hours in between.
A real headache. That free retrain for both war attacks was a big part of keeping me active in wars in spite of not caring about them that much. Cutting it to once a day is frustrating, given the odds of a total wipe on a war attack on any decently strong target.