Alright there are a ton of different supplements (I suppose nootropics should be added into this discussion too), and in the past, I've read that some of them should be cycled in order to maintain their efficacy. Unfortunately, I can't recall which.
The supplements I'm most interested in knowing cycling rules for (if there are any) are R-ALA, ALCAR, Piracetam, lecithin/choline, and a multi-vitamin. If someone wants to post a more comprehensive list of substances with their associated cycling methods, I certainly wouldn't be against that either.
Also, are there any criteria one can use to determine whether a supplement should be cycled in the first place? For example, direct neurotransmitter precursors should always be cycled.