Hello, I think an option to show an extra Submit/Next button for questions that support branching is a must. It would prevent poking over branching answers by selecting different answer choices in opening (branching) question. Submit/Next button should lock the selected option and only after the submission the following branching question will be shown. This is a kind of prevention to make a convenient choice based on information found in the following branching question.
From the moment of submitting the question, there should be no possibility to change answers for all questions (maybe only branching ones?) prior and including the question with Submit/Next button. If branching goes to the section, then there is no way back to the previous section.