Hi @Luca_Lattarini ,
It depends on your requirement. If you were to fire a page view call, you will need to go for s.t() call. Otherwise we should choose s.tl() calls for link calls (non page-view call; it doesn't count towards a page view). For example, if someone clicks on a link on your page which downloads a document, you wouldn't want to count that server call towards a page view. Another example, if someone clicks on a link on a page of your site to navigate to other sections of the site and if you would want to track the link click, s.tl() calls are the ideal scenario.
Hope this explains!