I want a game where i can add in magic items whenever I want not at certain levels because sometimes I feel like I have to just cram in an item or two just to be able to get them to the players without just outright saying "Okay here is a +2 sword".
The only math you really have to balance is the "to-hit" mechanic. Magic items without bonuses to hit may make a player a little more powerful but it wouldn't necessarily change the way the math works. If a CR 5 monster has an average AC of 18 and you have an average to-hit score of + 8 then having a magic item that enables you to do more damage will still be okay.
I think the hitting and getting hit parts are what needs to be looked at.
The only math you really have to balance is the "to-hit" mechanic. Magic items without bonuses to hit may make a player a little more powerful but it wouldn't necessarily change the way the math works. If a CR 5 monster has an average AC of 18 and you have an average to-hit score of + 8 then having a magic item that enables you to do more damage will still be okay.
I think the hitting and getting hit parts are what needs to be looked at.