Grandchildren Birthdays

One of my twin daughter has 8 grandchildren.  It is really something that all their birthdays fall in November
 and December.  It is like many times Christmas, over and over and it isn't even Christmas time yet. I don't know how they figure out what to get them when they also have to shop for Christmas.  Four of our kids were in November and December too so I know what they are going thru.  We used to get them mainly clothes for birthdays and maybe a game so there was something left to buy for Christmas.