Hello:
I could not find a source in my hasty skimming through the pages of Rev. Father O'Connell's works or in Matters Liturgical about the practice of a prolonged elevation of either the Sacred Host or the Sacred Chalice. I will look more closely at these tomes and others when the opportunity arises.
However, I will state that I too have heard from others that a prolonged elevation may be an abuse, and it endangers the safety of the Sacred Species. A Priest who has been officiating a liturgical function as intricate and demanding as Holy Mass, who moreover has been fasting and may have pertinent issues with health (such as age, weakness of limbs, &c.), ought not to risk dropping the Sacred Host or the Sacred Chalice by reason of such a prolonged elevation.
Some individuals have the mistaken notion (more in the practical order than theoretically) that the elevation is inherently necessary for the integrity and decorous confection of Transubstantiation, but it is really a distinct act, independent from the Consecration, and it is a later development in the history of the Roman Rite.
Another CathInfo member, "romanitaspress," may be of more substantial help for your query, as it seems that he is not to be surpassed in erudition regarding these matters by anyone in this forum.