Yes, it is actually a good thing to do. Having festivities images on your portfolio will increase your downloads. However please send and/or upload festivity content only when the date is approaching, preferably a month before and avoid uploading a few days close to the date as this assures more downloads and consequently more earnings. For example: If we are in the month of January, it doesn't make sense to upload Christmas content as the date just passed and you will not get as many downloads as if you would have uploaded it in November. But in January it would be useful to upload Valentines designs as the number of downloads will keep on increasing as we get closer to the date.