pros & cons of multiple apple ids

Where can I go to understand issues, pros & cons, arising from using multiple Apple iDs with multiple devices?

I have an older iPad with same Apple ID as my iMac in order to easily synch music & photos, via iTunes backup, but with new iCloud backup & sharing features added thru the years, I am unsure if this is the best approach any longer? but wonder how to make a transition to a better approach?

I have a separate Apple ID for my iPhone to segregate it from sharing and moving the same photos around, I like to get all my photos from various sources onto my iMac where they are organized, titled, reviewed and put into albums,, after which I backup to an Apple time capsule and synch the organized photo files with my iPad for mobility and display via Apple TV or whatever.

I guess I'd just like to read/understand some concepts or guidance about separate icloud accounts & separate Apple IDs etc, in order to understand if what I'm doing is a good way to do it or if there are other approaches that may be better?