I can't make my player to shoot faster (Check script for reference)

Hello everyone! I was making a player shooting script and was having some trouble. The normal shooting works just fine, but there's a problem with the part where I increase the rate of fire. There is a collider (which is a trigger) in the script, which activates the shooting frenzy for 10 seconds. But when I touch the collider nothing happens. Does anyone know what's wrong here? Thanks. using UnityEngine;

     public class PlayerShooting : MonoBehaviour
     {
         
         public int damagePerShot = 20;
         public float timeBetweenBullets = 0.15f;
         public float range = 100f;
         public float delay = 1f;
         float nextUsage;
         float timer;
         int time = 0;
         Ray shootRay;
         RaycastHit shootHit;
         int shootableMask;
         ParticleSystem gunParticles;
         LineRenderer gunLine;
         AudioSource gunAudio;
         Light gunLight;
         float effectsDisplayTime = 0.2f;
     
     
         void Awake ()
         {
             shootableMask = LayerMask.GetMask ("Shootable");
             gunParticles = GetComponent<ParticleSystem> ();
             gunLine = GetComponent <LineRenderer> ();
             gunAudio = GetComponent<AudioSource> ();
             gunLight = GetComponent<Light> ();
             nextUsage = Time.time + delay;
         }
     
     
         void Update ()
         {
             timer += Time.deltaTime;
     
             if(Input.GetButton ("Fire1") && timer >= timeBetweenBullets && Time.timeScale != 0)
             {
                 Shoot ();
             }
     
             if(timer >= timeBetweenBullets * effectsDisplayTime)
             {
                 DisableEffects ();
             }
         }
     
         void OnTriggerEnter(Collider c1)  //to increase rate of fire
         {
             if(time <= 10)
             {
                 timeBetweenBullets = 0.05f;
                 if(Time.time > nextUsage)                    //to make it execute once per second.
                 {
                     nextUsage = Time.time + delay;
                     time++;                                    //to count seconds
                 }
             }
             else
             {
                          timeBetweenBullets = 0.15f;
                              time = 0;
                  }
 
         }
     
         public void DisableEffects ()
         {
             gunLine.enabled = false;
             gunLight.enabled = false;
         }
     
     
         void Shoot ()
         {
             timer = 0f;
     
             gunAudio.Play ();
     
             gunLight.enabled = true;
     
             gunParticles.Stop ();
             gunParticles.Play ();
     
             gunLine.enabled = true;
             gunLine.SetPosition (0, transform.position);
     
             shootRay.origin = transform.position;
             shootRay.direction = transform.forward;
     
             if(Physics.Raycast (shootRay, out shootHit, range, shootableMask))
             {
                 EnemyHealth enemyHealth = shootHit.collider.GetComponent <EnemyHealth> ();
                 if(enemyHealth != null)
                 {
                     enemyHealth.TakeDamage (damagePerShot, shootHit.point);
                 }
                 gunLine.SetPosition (1, shootHit.point);
             }
             else
             {
                 gunLine.SetPosition (1, shootRay.origin + shootRay.direction * range);
             }
         }
     }