I never found a need for them, probably because the older keyboards didn't recognize them. As for playing smoothly, the hold features takes care of that.
All the best,
Gary

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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)