Look, I know Ornn is very exciting. Having a new character in your game is a very neat and infrequent experience. However, despite your excitement, you gotta stop upgrading your Infinity Edge before you build a second item.
As you can see from the list of Ornn’s upgrades above, all they give you are stats. More importantly, the stats are not that great.
Don’t get me wrong, extra AD is awesome when you are full build and looking for anything to spend your gold on, but it isn’t particularly efficient.
Usually when you complete a item you are getting a “deal.” All stats can technically have a gold value stapled to them, but full items come with discounts. You pay the value of the stats but get passives and other properties for “free.” Because these upgrades add absolute nothing outside of raw stat value, they are far less efficient than buying a new item. This is, in a nut-shell, why you almost always want to finish your item before starting a new one.
These Ornn upgrades are ways for you to increase your late-game potential past the natural limit.
It is meant to be slim, but meaningful. So when you upgrade the item mid game instead of buying a new one, you are delaying your power spike and paying through the nose for very few stats. Save yourself the headache and complete your build first. Once the game goes to 50 minutes, then you will be glad you have Ornn.