I'm gonna throw my two bits in here and say that a combo's length should be determined by your skill with any given character. wether it's mugen, or a tournament league fighting game, people are always finding something new. this will apply most aptly to any balanced character. dio by warusaki3 is one such character. in my opinion. well balanced and if you play your cards right can do massive combos. characters lacking a complex enough moveset will have a harder time for sure. but not impossible with the right tools. and outright OP and broken characters can often rack up to 999 with hardly any effort. i prefer the middle ground if not between balanced and broken somewhere. but hey. that's my two bits.