I also assumed that it instantly returned to the Sacred Realm once it's wish was granted. Remember the only reason that the triforce was even in the light world was because of Ganondorf touching it in OoT causing an imbalance and it broke apart. So each piece connected itself to an individual until it was finally reunited at the end of WW.
Through it's appearances in games, the triforce might actually have a specific resting place in the Sacred Realm. Ganon in ALTTP did not personally keep it guarded within his own impenetrable tower full of traps and loyal minions. He kept the triforce in the pyramid of power in the center of the Dark World where anyone could walk up and down at any time they wished. Only sealed inside and in a special room for it to float around and apparently greet newcomers. Why would he keep something so important to his superiority and power in a very obvious location and not in his glowing tower that is on top of a mountain outside the reach of most people while sealed with magic? Also after Link defeats Agahnim the second time Ganon retreats to the Pyramid and then tells Link
I never imagined a boy like you
could give me so much trouble.
It's unbelievable that you
defeated my alterego, Agahnim
the Dark Wizard, twice!
But I will never give you the
Triforce. I will destroy you
and make my wish to conquer
both Light and Dark Worlds
come true without delay.
His words "make my wish" could have two separate meanings here. He could be talking about his original wish to rule all the world, as in his original desire to do so. Or he was overpowered by some young Hylian and then ran to the Triforce's location to make another wish on the Triforce. By that time the Sage's seal on the Dark World was broken so he could possibly wish to have the Light World if Link did not arrive to stop him.
Later in OoT Rauru mentions that the Temple of Light which was built by the ancient sages houses the Triforce in the center of the Sacred Realm.
I am Rauru, one of the ancient Sages... Ages ago, we ancient Sages built the Temple of Time to protect the entrance to the Sacred Realm... This is the Chamber of Sages, inside the Temple of Light... The Temple of Light, situated in the very center of the Sacred Realm, is the last stronghold against Ganondorf's evil forces." — Rauru
It would not make sense for Ganondorf to wish to keep the Triforce in the Pyramid if it was the actually the Temple of Light. The temple was built by the sages and houses the chamber of sages which have repeatedly stood against Ganondorf and his plans for conquering Hyrule. He might not want to keep the Triforce in such a place if he had a choice in the matter. Even in the Dark world any lingering Sage spirits would plot against him. In ALTTP the Pyramid housed a Great Fairy that actually did plot against him by giving Link silver arrows and blessing the Master Sword telling Link how to defeat Ganon. It is not wise to keep the mystical object of godly might in such location surrounded by potential enemies and saboteurs like that unless it was the specific sacred location the Triforce returns to or remains on it's own.
The Deku Tree states that is rests at the point were the Goddesses left the world.
And golden sacred triangles remained at the point where the goddesses left the world. Since then, the sacred triangles have become the basis of our world's providence." — Great Deku Tree
So it is very likely that after a wish is made the Triforce returns to the location where the goddesses left it in the Sacred Realm. Otherwise Ganon in ALTTP might not leave it there. The ancient sages that built the Temple of Light might have known this as well and built the Temples of Light and Time to protect the Triforce instead of removing it to a safer location. Ganondorf of OoT had no trouble obtaining the Triforce once the Door of Time was opened showing that the sages possibly not move it, only protect the gateway to it's location.