Why not use the knife tool with mid-point snap (CTRL)? It requires no selection.
Also worth noting that in recent versions the Auto-Merge options and snapping can be used for this task as well. The Auto-Merge has a setting “Split Edges and Faces”. When it’s enabled, you can simply extrude a vertex and snap it to another vertex, or an edge center, and faces will be split automatically. One advantage over the Knife tool here is that snapping options include “Edge Perpendicular”, something that Knife sadly doesn’t have.
“Split Edges and Faces”
I have turn it on…no idea how to activate it…turned it back off.
What did you press to have that line following the cursor ?
Not K for knife ?
Hold up, just read through the answers…e for extrude…thanks for making that awesome video !!!