Hi Georgina - I have always found 360’s are more impactful when an action plan and regular check-ins (post the 360) occur to embed change. I have also found that it is more exciting for leaders when they action something small first, see change (either in themselves or their team), have a win, embed the change and then move to the next action. Hope this helps.
I love 360s as I think they can be such a valuable tool when done well. I use the Leadership Circle Profile which gives lots of qualitative and quantitative data, is research based, and allows you to easily see where you are most creative and reactive. It’s probably too heavy of a lift to do every 6 months, but it’s something you could do once/year. I’m a coach, so I pair this with 1:1 coaching and there’s lots of group work you can do with this tool (without revealing confidential reviews). Happy to share more if you’re interested!
There is a great book called 360 Degree Feedback; A transformational approach by Elva Ainsworth. Elva has spent over 20+ years in the business dealing with feedback and 360s. She has written a new book but its not available on Amazon yet but it is also good.