Well sorachi is kinda right
Older jump manga like saint seiya, dragonball,... were excellent in training chapters. Training was so important in those shounen manga. Training was tasted and didn't affect the manga in a negative way, better it affected the manga storywise in a positve way. What do we get now with recent shounen: training is almost 0% and if so, it's so short, meaningless or just a prelude that'll have its effect through a real battle...
Since this is a DA topic, it's kinda possible he's talking about DA then again we must be honest. DA could have ended/cancelled with a training chapter but the training just started for like 2-3 chapters when it was near dying. Sorachi is right. A manga can be decent to good but if you don't follow the trends then doing something like old good manga doesn't necessarily mean it'll work out.
I like training chapters a lot, imo they are always the best but then again I grow up watching anime (adaptation of older manga) where training was important. But that doesn't count anymore, we aren't (at least i am not

) shounen anymore
