Question about the Demonoire project?

what is the purpose of having this trigger once after the input checking?

[Player Walk]

// Allow the player to move in 8 directions but only change directions if a single direction is being pressed.

Keyboard and Gamepad controls are exclusively separated here to simplify things.

// Keyboard

----+ Keyboard: ↑ is down

--------+ Keyboard: [X] ↓ is down

---------> Player_Base: Simulate 8Direction pressing Up

---------> Player_Mask: Set Walking to True

--------+ Keyboard: [X] ← is down

--------+ Keyboard: [X] → is down

---------> Player_Mask: Set Direction to "Up"

----+ Keyboard: ↓ is down

--------+ Keyboard: [X] ↑ is down

---------> Player_Base: Simulate 8Direction pressing Down

---------> Player_Mask: Set Walking to True

--------+ Keyboard: [X] ← is down

--------+ Keyboard: [X] → is down

---------> Player_Mask: Set Direction to "Down"

----+ Keyboard: → is down

--------+ Keyboard: [X] ← is down

---------> Player_Base: Simulate 8Direction pressing Right

---------> Player_Mask: Set Walking to True

--------+ Keyboard: [X] ↓ is down

--------+ Keyboard: [X] ↑ is down

---------> Player_Mask: Set Direction to "Right"

----+ Keyboard: ← is down

--------+ Keyboard: [X] → is down

---------> Player_Base: Simulate 8Direction pressing Left

---------> Player_Mask: Set Walking to True

--------+ Keyboard: [X] ↓ is down

--------+ Keyboard: [X] ↑ is down

---------> Player_Mask: Set Direction to "Left"

// Gamepad

----+ Gamepad: Gamepad 0 D-pad up is down

--------+ Gamepad: [X] Gamepad 0 D-pad down is down

---------> Player_Base: Simulate 8Direction pressing Up

---------> Player_Mask: Set Walking to True

--------+ Gamepad: [X] Gamepad 0 D-pad right is down

--------+ Gamepad: [X] Gamepad 0 D-pad left is down

---------> Player_Mask: Set Direction to "Up"

----+ Gamepad: Gamepad 0 D-pad down is down

--------+ Gamepad: [X] Gamepad 0 D-pad up is down

---------> Player_Base: Simulate 8Direction pressing Down

---------> Player_Mask: Set Walking to True

--------+ Gamepad: [X] Gamepad 0 D-pad left is down

--------+ Gamepad: [X] Gamepad 0 D-pad right is down

---------> Player_Mask: Set Direction to "Down"

----+ Gamepad: Gamepad 0 D-pad right is down

--------+ Gamepad: [X] Gamepad 0 D-pad left is down

---------> Player_Base: Simulate 8Direction pressing Right

---------> Player_Mask: Set Walking to True

--------+ Gamepad: [X] Gamepad 0 D-pad down is down

--------+ Gamepad: [X] Gamepad 0 D-pad up is down

---------> Player_Mask: Set Direction to "Right"

----+ Gamepad: Gamepad 0 D-pad left is down

--------+ Gamepad: [X] Gamepad 0 D-pad right is down

---------> Player_Base: Simulate 8Direction pressing Left

---------> Player_Mask: Set Walking to True

--------+ Gamepad: [X] Gamepad 0 D-pad down is down

--------+ Gamepad: [X] Gamepad 0 D-pad up is down

---------> Player_Mask: Set Direction to "Left"

----+ Keyboard: [X] ↑ is down

----+ Keyboard: [X] ↓ is down

----+ Keyboard: [X] → is down

----+ Keyboard: [X] ← is down

----+ Gamepad: [X] Gamepad 0 D-pad down is down

----+ Gamepad: [X] Gamepad 0 D-pad up is down

----+ Gamepad: [X] Gamepad 0 D-pad right is down

----+ Gamepad: [X] Gamepad 0 D-pad left is down

-----> Player_Mask: Set Walking to False

----+ System: Trigger once

-> (no actions)