Good post on the joiner’s saddle. A lot of us use a horse and draw knife to initially trim squares into rounds. But this bench method seems very practical. If you don’t have a surface bench clamp I would suggest making the single move-able saddle longer and or wider so a bar clamp can anchor it down to the side of the bench.
Another method is to make a single quite long v-block (with a stopped end) that slips into the dog holes and accommodates a variety of lengths.