I think its important to provide opportunity for evaluation and feedback of synchronous sessions for many reasons:
1) Self-reflection is important, but it can feel a little limited in scope. By receiving feedback from participants, we get feedback from different perspectives that can inform our practice of what did and didn't go well, so we can continue to evolve. It also helps to determine where self-reflection might best be focused!
2) Opportunity for learners to participate in the improvement of an educational experience and the ongoing professional development of the educator is one that shows respect for what our learners bring to the classroom. It also helps educators and the community they serve to be connected in the co-creation of learning opportunities.
3) Synchro is an evolving field and in my opinion, we have a long way to go before it's really effective for a wide range of learners. Merging different capabilities between platforms is something I hope we see soon. So, with feedback we can continue to build on what is going well, and work on what does not, and continue to collect a "wish list" that has contributions from our learners.
Follow up emails are my favourite, but might be hard if I am offering live sessions every day. I think I will likely devise a quick "closing circle" style anonymous quiz or other that will collect feedback on the experience daily, just as I do in person.