[SDPhantom]

Ticks do change based on spell used, but the number of ticks always remains the same for the same given spell. For example, no matter how much haste a warlock has, their Rain of Fire will always have 4 ticks as long as they aren't being hit with anything. Pushback from damage shortens a channeled spell's cast time, therefore reduces the number of ticks the spell gives. Haste only scales the entire thing as a whole, shorter tick delays and shorter cast time.