Vertices not working? When I try to add to my plain by selecting two vertices and then pressing E it only extends the edges and not the entire plain how does one fix this?
https://gyazo.com/b46b4cd4c2bf68e416e14fb32ffef16b
You should check if those vertices are duplicates. It looks like vertices being overlapping (2 or more in the same space). It happens a lot when trying to extrude, then "forgetting" to move your extrusion

Correct this issue in EDIT mode. Select all by hitting A, then by go to MESH menu, then choose Clean up, merge by distance. If not, there must be something you are doing wrong when extruding, but I am almost sure those are vertices overlapping.