What is more common in your experience?  I know different judges have different preferences.  What % of judges ask for free stacking in your experience?

You have to do both.  You hand stack initially when the judges go over the dog and any time the judge is looking at the dogs, but you have to free stack on the down and back, and it is nice when you go around the ring to free stack when you get to the end.  The judge sometimes will look at you as you finish the go around.  It is also nice to have your dog looking the best whenever the judge happens to look up, even if they are just glancing down the line of dogs.  There are some judges though that say let your dog relax, I am not looking at your dog now (although these seem to be rare in my experience). Some judges like a nice free stack and some don't pay much attention.  I haven't really paid attention to the percentages though.

I haven't ever encountered that, but then I have only been showing for a couple of years.  Maybe some of the folks who have been showing allot longer have seen this and can respond.  You might want to PM singltrak and ask her has she has been showing her dogs for a long time.

i've had a few that ask for free baiting/free stacking even with my mastiffs and border terriers

A hand stack shows the dog at their absolute best and the free stack shows their natural stance.  Doing both is IMO the best as you get to see the dog in different ways.  Just like you go around the ring and then also do a down and back.  The judge gets to see the dog moving from the side, front and back.  I have even had judges line the dogs up with their chests forward so they can look at the fronts of all the dogs together.  Also, some judges use a squeaky to see the dogs reaction.  The idea is to look at a dog in a variety of ways to find the dog with the best conformation that day.  z

I have never had a judge say that we cant hand stack either. But I have been told to just free stack my dogs after they have already gone over them. Linda Riedel had the bunch of us in winners freestack our bitches I had no time to get bait when I was switching, so my bitch didn't care about looking at me and standing pretty, I lost that major because of it. Ms.Riedel even told me "Next time bring some bait!" Because she was not paying attention to me.

But to answer your question you should do both. Sometimes judges go by how good a dog looks stacked.

Julie