My experience is facilitating professional development workshops - non-mandatory, but apply to professional growth awards (aka raises). There some topics that are best taught specifically to new instructors. They need time to process fundamental concepts of teaching and learning. Their concerns and questions are about the foundations and groundwork. They are usually feeling their way, drawing on how they were taught, without understanding how that becomes "best practices". Experienced instructors in these sessions only heighten their anxiety about what they don't know.
In other sessions - applying technology, for example, a mix of experienced and inexperienced instructors often yields lively discussions and a wealth of ideas that are beneficial to all.
Mentoring and peer-to-peer reviews where there is a formal relationship are other ways to develop both parties. One of the models that seems promising is the "clinical" model - similar to the support provided to medical practitioners of all sorts. As I understand it, there are regular communications and a specific cyclical "process" that includes self-assessment, review, evaluation and improvement plan. Is anyone familiar with the model? Can it be adapted for ongoing higher education instructor education and training?