Chair Corner Brace versus Corner Block?

[Jan Bianchi]

Some chair designs call both for gluing a small triangular corner block where back rails (or front) and side rails meet the leg and then screwing a corner brace farther out into both rails. Other seem to accomplish the same reinforcement with a larger triangular corner block that completely fills the space--looks a little like an A? Is there some reason that the first two-step process would be stronger?

[Jay Allen]

The biggest reason is wood movement. The leg has the grain running vertically and the stretchers run horizontally. Gluing a big block between these two elements could eventually cause problems, probably splittng the stretcher. Screwing the brace allows for this and allows for a wider support (triangulation)

[Jan Bianchi]

If I read you correctly you think the larger block that completely fills the space isn't a good idea because it inhibits wood movement. So you would opt for a brace and not a block. But if the leg is moving side to side along the grain, and the rails are moving top to bottom along the drain, why do some designers advocate gluing an additional small block at the apex of the intersection in addition to the braces?