Comfort is a Key to Safety
As snowboarding instructors it is our privilege to take something we love to do and assist other people in learning it. We try to have a positive influence over our students so that they will continue to enjoy snowboarding long after they have learned the basics. The challenge for us is to get them through the basics as easily as possible. Something to help instructors with that challenge is adjusting their student's stance.
Most of our students are beginners and come to us from the rental shop with poorly adjusted equipment. Instead of taking the time to adjust it we usually just teach them with what ever they were given. As far as more advanced lessons, people tend not to know how to set their stance or they see how a pro rider rides and set their bindings the same even if they aren't the same height and weight as that rider. So and so is riding a crazy duck footed stance so they do to, without regard for their own comfort and physical needs.
We teach beginners snowboarding from the aspects of safety, fun, and learning. A person who's new to snowboarding is almost always doing it for the fun factor and a big part of that is not getting hurt. For instance, if someone has a 24 inch pigeon toed stance a fear block is caused because they are uncomfortable. This is an extreme example, but my point is when the stance or equipment is uncomfortable in any way, the student will be afraid to try things and have a difficult time enjoying the experience. If they are comfortable they'll be relaxed and willing to try things (like turns). This will almost always translate into more fun for the students because comfort is the key to safety, fun, and learning. If you take the time to make them more comfortable and they feel the difference it will also help them to trust you more.
If people's feet are too far apart or too close together there is a constant fight with balance. Instead of being able to focus on going toe up and toe down to do a heelside falling leaf they're fighting gravity just to stay up. As an instructor this makes teaching frustrating because the student will struggle. If we would take just a few minutes to adjust that stance the student could make their focus snowboarding and not worry about falling over.
As far as binding angles are concerned I think riders should experiment with lots of different angles/positions until they find something that is comfortable and allows an appropriate range of movement. A large part of more advanced riding whether its bumps, steeps, or halfpipe is the ability to remain comfortably in dynamic balance. If you feel like you're going to fall over every time you get more dynamic, progressing will be tough. Would any instructor who freerides with any regularity allow their stance to be set in a position that is uncomfortable? Why should we expect our students to do the same? They do not have the ability to adjust their body movements to compensate for a stance being set poorly, i.e.: too narrow, too wide, or extreme angles. Students haven't developed the muscle memory yet. In general, a stance that is similar to how they would stand if they did a squat in the weight room is appropriate for most students. Typically when doing a squat, your stance is approximately shoulder width or slightly over. Your toes are pointing in a direction that is complimentary to the mechanics of your body, which allows for efficient flexion and extension. This all leads to how your legs, knees, and hips are aligned and which way your knees and toes point when flexing down with your legs. Some people can have their toes pointed out severely and their knees will go straight forward while others need their feet to be straight for their knee's to go straight. It relates to how each individual rider is built.
Another important point that ties into all of this is how tight a student's boots are tied. Many begin with their boots barely tied or tied loosely. When snowboarding we make movements with our bodies, especially our lower bodies, that induce a reaction from the snowboard. Boots transmit the movements to the bindings which transmit to the board. Loosely tied boots give little or no support, so require more movement to achieve the same response. This results in more work/energy expended and less effective riding over time. How many students, especially younger students, tire quickly? They are using muscles that are not typically needed so it is crucial to make their movements as productive as possible.
So to wrap it up, try to take a minute at the start of your lesson to check stance and boot fit. These things are key to our students feeling comfortable and being in control from the very first thing they do. I guarantee it will make you a much more productive instructor and your students will show more progress and have more fun as a result!