I inherited an on-prem Exchange server hosting tons of Public Folders for contacts and emails and other documents. Also in there is called their "Master Calendar", which has been used for many MANY years. Before being cached, it can take up to 5 minutes to download before displaying the calendar.
We migrated to O365, everything including the Public Folders is there now. It's great, but the company is addicted to this damn thing. If you want to schedule a meeting, you have to check their personal calendar, AND the Public Folder calendar to see if someone's available. Also, you need to remember to put yourself there just in case.
Some problems with this is speed: it's very slow to load even cached, and online accessibility: Public Folders are not available in web or iOS.
I tried migrating everything into an Exchange Group, but when I did I...