In essence, you're intended to, in the most optimal circumstances, end on:
ABC Dragon Buster + Therion King Regulus + Crystal Wing Sychro Dragon + I:P Masquerena + S:P Little Knight
I'd usually like to prefer to have another open slot to tag out ABC Dragon Buster at any instance but S:P Little Knight is a decent enough protector both when your ending your first-turn after building your board and during your opponent's next turn. Furthermore, the ability of cards like S:P Little Knight and Therion King Regulus to remove themselves from the field after doing their job leaves you open to being able to tag out ABC Dragon Buster thereafter.
I intend to experiment with this further. It certainly invites consistency to ABC that the deck lacked last I played the game to the point I'm considering ditching the Pots of Prosperity or getting by with but a single Union Driver since the danger of your entire gamestrategy falling to hell as a result of dead drawing your lone copy isn't that much of an issue anymore. Perhaps the side and extra decks needs more work, as well. I imagine most people would tell me to drop Borrelsword but I like having that additional boss monster so as to have more options to go into during a battle of attrition with battles of attrition being what ABC - with its ability to recycle and abuse resources - excels at.
All in all, I'm happy to hear suggestions.