Breadboard ends were always confusing to me because they are trotted out as a solution for movement yet they solve two quite different problems.

On flush, jointed boards, they are a permanent jig to hold the ends in vertical alignment. Imagine taping your fingers together to keep your fingers flat. Lateral movement is impossible because the boards are glued tightly together.

If you’re concerned about lateral movement then the more important concern is to have gaps between the boards. The bread board end is now a rail in which your boards can slide like wobbly carriages on a train track: aligned in one direction (up/down for a table) but with the ability to move independently in another (across the width of the table.)