Do you recommend puppy classes where puppies are turned loose together to “socialize” ? 

We don't recommend this type of class, we often get puppies here locally brought to us that participate in an area trainer's puppy classes where they turn all the puppies loose together. Those pups that come to us after attending these classes are often fixated on other dogs and pushy or adversely intimidated by the presence of other dogs. I want my pups and dogs to be comfortable in the presence of people and other dogs but not overly excited, fixated or worried. Neutrality to people and other animals is the goal.

You can read our definition of socialization here.  How To Socialize Your New Puppy

I don't mind if my dogs/pups have some family friends and a social circle of dogs that we see regularly but I don't like the group puppy play sessions and never would put one of my own puppies in that situation.

These classes sound like a great idea and often really appeal to the puppy owners but I honestly feel that it’s not in the best interest for many of the puppies that end up in these classes. This is based on our personal experiences here helping pups work through issues that were created from a general misunderstanding of what socialization actually should entail.