I recommend asking
1) What does my deck have that is most easily recovered by Puzzle of Time and not other cards?
2) How much benefit will I receive from having this added option to get them back?
3) Can I make room for them (includes match up considerations)?
That might seem out of order, but if I personally find that if I start by asking myself if I have room for any card, the answer is "No", I change nothing, and then I lose because my deck is out of date. XD I added the note because (as others already pointed out) if Item lock is already a problem for your deck, this is going to make it even more vulnerable since its an extra 2-4 slots of Items that are already likely to get "stuck" in hand.
Special Energy and Ace Spec cards (in Expanded) are the most obvious to uses for Puzzle of Time but it is also great for reclaiming spent TecH that otherwise isn't so easy to reuse. Even without either of those first two, if you have a toolbox like deck, it may be useful so that a single copy of Startling Megaphone, a particular Pokémon Tool, even sometimes a particular Pokémon can return to hand directly from the discard pile.