It’s for both I believe. Using the dimmer as an example, if you hold the up paddle on the dimmer, it doesn’t start brightening the light until a few ms (hold delay) have passed. I believe the explanation given was that it’s not sure about whether you want to dim or if you want to simply turn on the light (but are pressing for too long). It’s the same story with sending the zwave hold events. It waits for the same amount of time.
I believe a bunch of folks felt that the switch waits for too long before it starts dimming up or down and wanted that delay to also be configurable. Hope that makes more sense.
BTW, because the On/Offs also have the zwave hold events, we were hoping to be able to configure the delay for the on/off also.
I should also add that I previously asked @EricM_Inovelli about this and he said he believes the configurable delay would be for both: