Conditional Confirmations aren’t needed. By the time you’re old enough to be Confirmed you’re at the age of reason (age 7 or older) and you’d remember you were Confirmed.
So you remember getting confirmed when you were seven years old and at that age your understanding of the validity of sacraments, and how they are to be performed, was at best incomplete. And then 20 years later you learn that the bishop who confirmed you was excommunicated as a heretic six months after your confirmation and had questionable views on how to confirm. Might there be doubts?
Or say it’s the year 2025 and in the midst of a war in Africa, a group of priests of the Ethiopian Orthodox Church form a group separate from that church for political motives, and some of them have dissident politically motivated theological views. Fast-forward to the year 2050 and your aunt and uncle who raised you after your parents were killed in that war tell you that a priest of that group baptized you. Your parents were said to have been there at the baptism, but the priest was killed when a missile struck the building and destroyed the building and the records. In 2050 you decide to become a Catholic. A question arises: did that priest in 2025 validly chrismate you, in accordance with the standard practices of eastern Christianity? Might there be doubts?
Closer to home, I find it mentioned that some priests in Mexico confirm infants immediately after baptizing them. It seemed as if some people do have doubts.
Maybe with ordinations it’s more complicated. Suppose a bishop who ordained you is found to have falsified his identity in order to use someone else’s credit card, and it’s not clear whether he was really a bishop, or the person whose credit card he stole was a bishop.
Or (more realistically?) the bishop who ordained you is from a schismatic group that you formerly belonged to before you became a Catholic, and that group’s record-keeping is sloppy. Was he really a validly ordained bishop?
But some answers spoke of what would or could happen in hypothetical circumstances (as I did above). Is there hard evidence about the number of times conditional confirmations or conditional ordinations actually
have happened in reality? E.g. have there actually ever been any conditional episcopal consecrations?