Well generally speaking Navigation Mesh have very little to do with Collision., but they can be used to Optimise Collision Checklists.
In fairly basic terms...
A Navigation Mesh, is a Network of Path Nodes and Connections that allow an AI both Traverse and make decisions about said Traversal of the Map.
Beyond this you can add additional elements, such-as "Item Node Connections" that allow the AI to know what Items are nearest which Node; and Path Node Volumes so you can have Hierarchal Collision Object Lists; as these can allow you to determine the level of Priority of Interacting Objects.
As such you can either update interactions less frequently or simply ignore them as the Player will never see it.
Now as you can imagine this can dramatically reduce overhead on performing such tasks.
Pathfinding is an excellent example as, rather than using Voxel or Ray Marching to determine routes an AI can take... well they already "Know" the Map, thus can simple pick the correct route.
If you want your AI to gradually learn over time as it plays... you could combine Ray Marching with a Procedurally Generated NavMesh., so as the AI learns the map; it gains better understanding of how to Navigate and thus make more informed decisions.
Without a NavMesh for example., the AI has no way to predict where a Player is Headed... as well it doesn't know where any Items, Interaction Points, etc. are in relation to it... instead the Pathfinding is just going to find the Shortest Route to the Players "Last Known Locatoin"
Where-as with a NavMesh; it can see what Path Node the Player is in and their Direction of Travel; so then follow said Paths to determine "Likely" Destination Points.
Then make a decision (I'd recommend via Fuzzy Logic) where it thinks is most likely the Player is headed, and/or plan a new route based upon what Resources (Ammo / Weapon / Health) it thinks that IT needs.
What I'd recommend is playing with NavMesh in Unreal Engine 4., as you can manually build them with the built-in tools.
This can give you a much better and practical understanding of what they are, and what they do.
If I can find the time I'll craft an example in AppGameKit / DBP that showcases the benefits of them with AI.