Follow-up to the magic system in [Artifacts not being used for war](https://worldbuilding.stackexchange.com/questions/184528/artifacts-not-being-used-for-war) and [magic that replenishes with time](https://worldbuilding.stackexchange.com/questions/184155/in-a-world-with-regenerative-magic-why-would-creating-an-item-not-allow-you-to-r)

In a world with regenerative magic, the average human doesn't know or generally use the pool of magic they have within them. Normally, creation of magic items causes the magic needed for activation to be reallocated to the item until it is destroyed or removed.

My enterprising mages have created a new Runic Attenuation Band which allows them to bypass fully linking a portion of the creators magic at the cost of a much lower pool of magic able to be utilized. The creators don't put any magic into the item and instead it has an empty reservoir that is filled by the user.

These minor items take a period of about a day to reserve space within the users magic supply to be able to connect and fill the reservoir. A completely normal human can only attune to 3 such items at a time. An Archmage can also only attune to 3 such items.

I have my base magic system. I have the end result of only being able to attune to 3 of these rings. Why is my magic reservoir only able to accommodate 3 rings?

What practical reason would cause them not to be able to attune to more?

* Answers should not be story based.
* Social restrictions are not allowed.
* Rings causing interference with the magic or each other is off-limits.
* The answer should apply equally to people with low capacity reservoirs and people with extremely high capacity resevoirs.
* The use of rings has no differences in consumption based on skill of the user.
* There is no "pipe" that magic flows out of. A user could put all their magic into a single attack rapidly.