If you were to take Polyjuice, then clip hair from yourself (so it would essentially be the hair of the person you transformed into), could you create more Polyjuice to transform into that person using that hair?
Barty Crouch Jr. kept Mad-Eye Moody alive in his trunk to find out information about Moody's behavior as well as have a continued supply of hair from him. This implies either that Barty Crouch Jr. is unaware that such a thing is possible, or that he knows it wouldn't be so he ensured he'd have a supply of hair that would actually work.
“Then I packed up Moody’s clothes and Dark detectors, put them in the trunk with Moody, and set off for Hogwarts. I kept him alive, under the Imperius Curse. I wanted to be able to question him. To find out about his past, learn his habits, so that I could fool even Dumbledore. I also needed his hair to make the Polyjuice Potion.” - Harry Potter and the Goblet of Fire, Chapter 35 (Veritaserum)
In addition, Barty Crouch Jr. does take hair from Moody, since the real Moody is shown to have some missing.
“His wooden leg was gone, the socket which should have held the magical eye looked empty beneath its lid, and chunks of his grizzled hair were missing.” - Harry Potter and the Goblet of Fire, Chapter 35 (Veritaserum)
Dumbledore explains that Barty Crouch Jr. needed to keep Moody close by so he could get hair from him to continue to make the Polyjuice Potion. If Barty Crouch Jr. could instead use his own hair after transforming, this would be an unnecessary risk to take.
“The impostor needed, of course, to keep the real Moody close by, so that he could continue making the Potion. You see his hair …’ Dumbledore looked down on the Moody in the trunk. ‘The impostor has been cutting it off all year, see where it is uneven?” - Harry Potter and the Goblet of Fire, Chapter 35 (Veritaserum)
If he could have instead have locked Moody away elsewhere, keeping him at Hogwarts surrounded by skilled wizards like Dumbledore would be unneeded, and brings a higher risk of his plan being discovered.
Well, the way I see it. It would probably work if you just wanted to transform multiple people at once but only had the single original hair to make the first dose. Then you could take the transformed hair at that time and transform more people.
That being said, the potion would likely wear off of the hair eventually and then you'd be left with the original state. That is based on the presumption of course that magical energy works kind of like thermal energy and is constantly attempting to return to a state of equilibrium with its outside environment. I'm just basing that off of how wards frazzle over time. Then again, they're exposed to outside forces putting constant pressure on them. Cursed items from vaults tend to hold their curses for a lot longer. But, I'm just assuming that cursing those things probably involved arithmancy and rune magic which seems like longer lasting types of magic that are also likely applied to the creation of wards.
Of course, rituals would also likely extend the duration of a magical infusion by binding it to some sort of outside force like a person in a blood ritual or an existing output of magic like I imagine family portraits or the suits of armor at Hogwarts are.
I suppose what I'm trying to say is that infusing a person and in turn a body with a potion and its duration likely depends on the magical potency of the ingredients. And when that duration expires and the magic is no longer in effect it returns to its original state. So you would likely be able to use the hair as long as the potion was in effect but after that, it would return to the original hair.
Again, that's my take on it based on my readings and theoretical magical knowledge.