Photowalk is not a word that can be easily be found defined in a dictionary. I understand it to mean:
An informal organized gathering of people whose intent is to stroll around leisurely taking photos, enjoying themselves, and learning from one another through interaction and observation.
No explanation is necessary. We all benefit from instruction. Regarding workshops in general, photography related or not, I always take something away from the experience.
Workshops allow for more individualized attention. Studies have shown that more is accomplished with a smaller teacher to student ratio. A smaller group size allows for more opportunity for communication. Sometimes individual student/teacher time is included during a workshop. Before a workshop I determine what it is that I want to get out of the workshop. I prepare a list of questions ahead of time. Many of these questions are naturally answered through the content of material presented. The other questions I will ask the instructor during a one-on-one session.
Workshops typically consist of ten or less students. In my formal career I have had the opportunity to present, teach, and mentor numerous times. There are benefits to learning in smaller groups. I have seen it with my own eyes. In larger groups and in classroom settings it is harder for people to speak up and ask questions. I once taught a night class at the local college that only had seven students enrolled. The restraint and sheepishness of students was almost non-existent. In that situation I felt less like a teacher and more like a big brother type of mentor. The atmosphere was very relaxed. People felt comfortable. I have observed the same type of social synergy in photography workshops. People interact, they speak up and communicate.
Workshops are generally scheduled for a full weekend or less. I've heard time and time again that the best way to become a photographer is to keep your day job. Like most of us, I have a 9 to 5 career. There isn't time available in my busy life to enroll in formal photography or art classes. Workshops are great because they generally occur over the weekend. They are usually held at a very great location and thus can feel like a mini vacation. One day workshops that are held on a Saturday seem to fit me well. My wife and I will generally travel to the workshop destination on Friday night after work. Saturday day is taken up with me at the workshop and my wife shopping or checking out the tourist attractions that are offered. We meet up in the evening for dinner and a night out on the town. I also use this time out with my wife to get some street shooting in as well. It's great to multitask street shooting while out on a date with your love. The day ends up being a full day of photography for me.
People like to spend time with other like minded people with the same interests. Workshops mainly consist of time in a classroom followed by shooting time. During this shooting time there is much interaction. This is where I approach or am approached by others to chat about what has previously discussed during the day. Conversations typically start with "I really agreed with your comment regarding......" or "I have the same camera. Do you like the lens you are shooting with? I've considered buying it." Advertising for workshops should include "For sale: instant friends, just add cameras". I have met many great people attending photography workshops. Someone usually facilitates email address exchange at the end. I can say that I keep in contact with some people I've met through email or simply following and commenting on their blogs, social pages, etc.