From Minecraft Parkour Wiki

When building a setup for blip-up, the rule of thumb is have both surfaces at the same tier relative to the starting height.

  • The effect of a blip-up generally increases the faster the player falls.
  • The setup should be carefully adjusted to leave as much space as possible between the player and the ground on the landing tick.
  • The height gain could be anywhere between 0b and 3.92b (terminal velocity). The taller the wall, the less effective the setup becomes.