You can toss any other idea than Puzzle of Time for being to clunky, take up valuable space in your deck or by wasting an attack / an energy attachment.
However the answer to your question isn't found in discard pile recursion, but rather at the step beforehand. Sycamore / Juniper have been the go to supporter alongside N for years, yet the printing of Cynthia has given us more options (that anyone familiar with Legacy is well aware of).
If your deck relies heavily on Rare Candy that the optimal decision is to cut down on Sycamore and add more Cynthia (i.e. 4-3-2 line of N, Cyn and Syc). Throwing out Sycamore completely is ill advised, as the raw draw power, as well as the ability to discard cards you don't need any more / need to be in your discard pile is crucial for pretty much every deck.
However, we all know that sometimes the worst scenario happens and we are stuck with an awful hand, that forces us to discard our resources with Sync, if we want to come back into the game.
Well, are we ?
Lets imagine we got our basic cards on the field and our hand is cluttered with Sycamore, Energy, some utility (no UB though) and Energy cards. In this scenario we have two options: We either play Sycamore, discard our resources and hope to draw into something better, or we skip the supporter for the turn.
While the later option seems like a bad idea, let's look at it a bit more. Given that we already have our Basic Pokemon in play (maybe even two of them), we need to hit either the stage 2, an UB, Tapu Lele or one of your non-discard supporters. Depending on the deck you play those can easily take up ~ 15 cards in your deck not counting any deck specific search engine you are running.
Skipping Sycamore on the first turn is obviously quite the loss of tempo and if I only had to discard 1 out of 4 Rare candies I'd probably always take the Sycamore, but then again it all comes down to the situation in game, because you can come up with infinite scenarios and the outcome will vary slightly every time.
Here comes the interesting part though: so far we looked at the whole situation in a vacuum, assuming our opponent is the goldfish. However, now imagine being in your opponents shoes. Your basic Pokemon give an obvious hint towards the deck you are playing. It's also obvious that you need a Rare Candy and that you didn't play a supporter. This could either hint at a blank hand, or hint at you holding stage 2 and Candy, to play on the following turn. Which leaves us with the question: does our opponent want to N us ?
Dunno if I answered your question ( I kinda forgot about it mid way), but I hope you enjoyed this short interlude never the less .
The shadows of the abyss are like the petals of a monstrous flower that shall blossom within the skull and expand the mind beyond what any man can bear, but whether it decays under the earth or above on green fields, or out to sea or in the very air, all shall come to revelation, and to revel, in the knowledge of the strangling fruit - and the hand of the sinner shall rejoice, for there is no sin in shadow or in light that the seeds of the dead cannot forgive...