In making mortise and tenon joints, one of the challenges is to make sure the tenon fit into the mortise so that its tight, but not too tight. There are all sorts of jigs and methods to do this on the tablesaw, with a router table, with hand tools, etc.
In this case, I’ve got a pair of cabinet doors I’m building for a display cabinet, I’ve got the mortises cut first (you typically cut the mortises first) and I’ve rough cut the tenons. In order to get the width exactly right, I’m using a router plane to cut the tenons down to width.
A router plane (not a router) has an “L” shaped blade which sits below the plane, and “roots out” the wood so that its all the same level. You can dial the depth of the cut down by miniscule amounts and get it exact – a very good tool for dados, tenons, etc. Because its hand powered, you can creep up on an edge without worrying the power tool will “run wild.”
Its another situation where a hand tool can actually do a job better and more accurately than some power tool.
Kevin