Seeing a visit that says "single page" can be confusing. This is because time spent on a web page is measured a bit differently than you may think!
Leadfeeder measures visit length by tracking the amount of time between a visit on one page of your website and a visit on another page of your site. If a visitor only hits one page then Leadfeeder will display that visit as a length of "single page".
This is also called a 'bounce', meaning the visitor went to one page then 'bounced' away. You can see below we have a 'bounce' and a long visit from two different visitors.
A good way to visualize this is as a horse race. The starting point is the starting gate, this is your first-page visit. The end-point is the finish line, this is the next page visit.
You can easily measure how fast a horse got from the starting gate to the finish line because there is a clear stop and start. This is the same way with websites, we can measure the time between two-page visits.
However, if the horse was never seen at the finish line how would you know how fast it got there. It could have never started running, or perhaps never stopped at the finish line. Having a clear start and stop is needed to measure the time in between.
Bounces aren't always bad things, especially if you have a single-page site or pages that are long and give the visitor everything they need. They are worth keeping track of though.
NOTE: If your site is a single-page app (SPA), read here how to track the length of the visit with Google Tag Manager.
If you see important pages with multiple links and calls to action 'bounce' you may want to give them a look and make sure that the content is doing its job for your visitors.