Can help between islands be arrange??
There is scheduled public ferry service like subway and bus service in a big city
Check the ferry timetables - they are published. Some give you time on the various islands, but with set times you need to make allowances for how much time each island takes.
Referencing my previous answer to your Naoshima question, my last visit it did not make sense to do the other "art" islands, so we had three days on Naoshima.