An excerpt from Joshua Klein’s forthcoming book, Joined: A Bench Guide to Furniture Joinery:
“Here is one reason I prefer to have my workbench against a wall: avoiding the use of clamps in paring operations. To pare chamfers onto the tenon for ease of assembly, I butt the rail against the wall. This is so much faster than messing with clamps or a vise and allows me to instantly adjust the workpiece.
A related technique is pinning the work with my hip into a fixed point on the bench. Depending on the stock’s length, sometimes it’s the metal-toothed bench hook (planing stop) or in this case the wooden side rest. I’m sure some would think this is silly and that I should really just put this thing in the vise, but each chamfer takes no more than 1 or 2 seconds and there’s no way I'm going to adjust the stock in the vise between all of those cuts. My goal is swiftness.
The chamfers don’t need to be huge – just enough to avoid getting hung up on errant junk in the mortise corners.
Now that the tenon is trimmed to size, lay it on the leg to mark the top and bottom of the mortise. Stab these two marks with your knife. You will want at least an inch of material on the leg above the rail. This “horn” is extra material to provide strength during mortising.”