How does Fastest load balancing work in v14.1?

The Fastest load balancing method is described in the v14.1 BIG-IP Local Traffic Management: Basics manual with the following:

Description

The Fastest methods select a server based on the least number of current sessions. These methods require that you assign both a Layer 7 and a TCP type of profile to the virtual server.

When to use

The Fastest methods are useful in environments where nodes are distributed across separate logical networks.

The help documentation available on a v14.1 BIG-IP LTM system describes Fastest in a somewhat different manner:

Passes a new connection based on the fastest response of all currently active nodes in a pool. This method might be particularly useful in environments where nodes are distributed across different logical networks.

The F5 LTM Configuration course for v14.1 describes Fastest in yet another manner:

Next connection goes to node or application (member) with fewest outstanding Layer 7 requests

Three sources, three different descriptions of how Fastest load balancing might work.