How to extrude to meet an angled face? Imagine extruding a wall profile from the flat floor plane, constraining the extrusion to the Z-Axis. It must meet the pitched ceiling angle above. Is there a simple way to perform this without knife cuts after the fact? I'm currently using the TinyCAD add-on to extend edges to the ceiling face, but this is tedious and I have to perform this function very frequently. Any simpler ideas that I've missed?

Thanks for the clear reply, Robin. Your second solution worked perfectly. Those snap options do so much more than I realize. The first, however, is still giving me trouble. The vertexes do not snap to the roof angle, and they are variably snapping to whatever point on the roof edge that I am hovering over. I try it a second time with "Align Rotation to Snap Target" at the end of the gif, the result is just crazed. I must have some setting incorrect. See here:
Set the snap options 'Face', and 'Project individual elements':





Select the top face(s) of wall, and have a view open looking down the desired axis of projection. (The right-side one, here)





With the mouse in the projection view, Hit G