Tiled Movement Inputs are Inaccurate

Hey, good afternoon! I am currently working on a first-person dungeon-crawling game using Unity 3D. Right now, I have given the player the following inputs:

1. Move Forward, Backward

2. Strafe Left, Right

3. Change the direction they are facing w/o moving

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What I need help with is the first 2 input types: moving and strafing. The player is supposed to only move a specific unit of distance per input, as if they were moving between spaces on a chessboard (tiled movement).

When run through Update, the player moves in strange intervals that sometimes change intermittently. (Example: The player will move 0.78 units for the first input @ runtime, but then only 0.3 units the next time I press the same input.)

When I run inputs through FixedUpdate, the intervals are what I want them to be (1 unit of distance/input), but inputs get lost/delayed far too often. It's my understanding that this is due to how Unity handles physics calculations - is that right?.

I've provided the following:

• My code

• The current view through my player

• The tutorial I used to help me understand the movement

  ---

     using System.Collections;
       using System.Collections.Generic;
       using UnityEngine;
   
       [RequireComponent(typeof(Rigidbody))]
       public class Movement : MonoBehaviour
       {
       public GameObject Player;
       Vector3 destination,
       currentDirection = Vector3.zero;
       public float Speed = 5f;
       float rayLength = 1;
       bool canMove;
   
   
       // Update is called once per frame
       void Update()
   
       {
        
           // PLAYER MOVEMENT IS HERE
   
           if (Input.GetKeyDown(KeyCode.W))
           {
               transform.position += transform.forward * Time.deltaTime * Speed; //MOVE FORWARD
           }
           else if (Input.GetKeyDown(KeyCode.S))
           {
               transform.position -= transform.forward * Time.deltaTime * Speed; //MOVE BACKWARD
           }
           else if (Input.GetKeyDown(KeyCode.A))
           {
               transform.position -= transform.right * Time.deltaTime * Speed; //STRAFE LEFT
           }
           else if (Input.GetKeyDown(KeyCode.D))
           {
               transform.position += transform.right * Time.deltaTime * Speed; //STRAFE RIGHT
           }
   
           // THESE CONTROLS DETERMINE WHICH DIRECTION THE PLAYER IS FACING; CAMERA IS CURRENTLY A CHILD OF THE PLAYER, SO IT ALSO MOVES ACCORDING TO THESE CONTROLS
           if (Input.GetKeyDown("q"))
           {
               Player.transform.rotation *= Quaternion.Euler(0, -90, 0); //TURN CAMERA/PLAYER LEFT
           }
           if (Input.GetKeyDown("e"))
           {
               Player.transform.rotation *= Quaternion.Euler(0, 90, 0); //
           }
   
           if (Vector3.Distance(destination, transform.position) <= 0.0001f)
           {
               transform.localEulerAngles = currentDirection;
               if (canMove)
               {
                   if (Valid())
                   {
                       destination = transform.position;
                       canMove = false;
                   }
   
   
               }
           }
       }
   
       bool Valid()
       {
           Ray myRay = new Ray(transform.position + new Vector3(0, 0.5f, 0), transform.forward);
           RaycastHit hit;
   
           Debug.DrawRay(myRay.origin, myRay.direction, Color.red);
   
           if (Physics.Raycast(myRay, out hit, rayLength))
           {
               if (hit.collider.tag == "Wall")
               {
                   return false;
               }
           }
           return true;
       }
   }