To follow up on that with design concepts, all of those corners will release water, allowing the board to redirect faster. It does nothing to increase hold.
corners and wings break the outline, curves smooth the outline and create smooth turning.
youre going to get much more results with changes to overall outline, rocker, foil, and fins. Tails are icing on the larger cake.
Respectfully, in a very basic sense, I think changing direction or redirecting is mainly a board size issue (length and thickness). Sort of like how taking a sharp turn in a car is easier/harder in a smaller/larger vehicle, respectively. I don’t think it has anything to do with water being released off the corners.
As far as tails go, I think tails are huge on a design and not just icing on the cake at all. I think of tail shapes like wings or tails on an aircraft. They dictate almost the entire maneuverability of the aircraft. Just like tail shapes dictate the maneuverability of a surfboard. Pintails are known for more hold on larger waves. Wide tails for more planing speed. Swallows for grip. Diamonds for more pivot. But the tail shape is a huge aspect of a surfboard design.
I have had several boards with the same rocker, width, length, etc, and the only change was the tail shape and they rode totally different. The hydroshort as example, I had a roundtail and a squash tail and the roundtail had more hold and better pivot, but the squash went better in smaller waves and felt better. Same thing with the OB1/Cymatic as a diamond tail or battail. The result – more pivot on the diamond tail and more grip on the battail.