My rules on ab training:
1. Fuck side bends or weighted obliques, they are worthless for aesthetics and are more detrimental to a V shape than anything.
2. Fuck weighted ab work, simply not necessary, strong contractions and bodyweight is all that is needed for a great set of abs that look proportional. The abs are one of the few muscles that grows larger with age, so the goal is to keep them smaller and more in line with being "in shape" and not overly developed. Weighted ab work is out for me.
3. Abs are a good sign of what type of condition you are in. Like Serge Nubret once said, his ab training was looked at more like cardio for his midsection, I'm definitely in line with this train of thought now.
4. Abs requires nothing fancy, basically 2 different exercises for me, either a sit up motion of bringing the body to the knees or a leg raise motion of bringing the knees to the body. Anything else is unnecessary and the obliques will come in with a good diet and the tighter you get, no fancy twists or oblique work needed.
That's all for now, based on 25 years of trial and error, LOL