My sample size was 83 adventure loots. It ran throughout the event, although the returns as more skewed towards the later part of the event, as that was when I had more free days to play. I will say there was a lot of variation in the days, even getting at least one day of no returns and one day of only 0 and 45 egg returns. From the overall count, they evened out over the run as one would expect with randomly generated returns.
Do people really think that there are different returns set for different people in the game? I do not know the details of how the number was derived on the wiki, as in sample size and the number of players collecting the data, but the only thing I seem to have done differently from the other players who have posted was to collect all the return information. And when saving and copying the information directly, it produced the same information as the other group that was likely to have done the same. Conversely, the many who have voiced their returns have done it using estimates or partial data, which is obviously open to bias. If I were posting based on single days, I could quote statistics as low as 50% 45 returns and 50% 0 returns, and even 100% zero returns; I could also give a rate of 50% 90 returns, 25% 45's and 25% 0's.
As for the 55% no drop rate, I would ask for the same information about sample size, as well as the sample sizes used to provide the comparisons.