Below code alerts every 5 seconds for 1 minute.

5000 milliseconds = 5 seconds. 

Sample Code:


LWC HTML:

1. <template>    
2.         
3.     <div></div>  
4.     
5. </template>  

LWC JavaScript Controller:

1. import { LightningElement, track } from ‘lwc’;    
2.     
3. export default class sample extends LightningElement {    
4.     
5.     @track progress = 5000;  
6.   
7.     connectedCallback() {  
8.           
9.         this._interval = setInterval(() => {  
10.             this.progress = this.progress + 5000;  
11.             alert( this.progress );  
12.             if ( this.progress === 60000 ) {  
13.                 clearInterval(this._interval);  
14.             }  
15.         }, this.progress);  
16.   
17.     }  
18.     
19. }