What are Weekly and Instant crawl requests on Link checker feature?

Weekly Crawl and Instant Crawl Request:
Website Crawling the website involves huge budget, server resources, storage overheads and hence this crawling program is limited to a week's time. 

Elite Site Optimizer Crawler will crawl the user's website on a scheduled weekly crawl basis. 

At some moments, if the website gets updated for any changes or fixes for on-page issues, changes to the links or changes to the content or changes to the page structure or changes to other web elements. 

In such events, the user may want check if there are on-page SEO issues prevailing on the web page without waiting for the ESO Crawler's schedule of another week wait time. 

The user can request for the website crawl and ask for specific report crawl instantly depending on their subscription plan allowed quota requests per week.