I started gaming with AD&D 1e. We didn't use unique or home grown magic items, we just used the DMG and let the dice fall as they may.
As I got older, I saw a value to unique magic items. My players, all of whom new the DMG front to back, back to front, side to side and all manners in between, needed to be surprised and challenged.
So, I started to tweak magic items, to keep my players guessing.
Years later, I even wrote a product or two with some of my creations.
My question to you is - do you design unique magic items, do you source them from others places or do you stick to the book?