Gaidens, or Paralogues as we call them now, are pretty sensible in Three Houses. In fact I'm surprised they weren't done this way long ago. They're entirely side character focused and unlocked simply by having a character, or multiple characters alive and unlocked in your army by a certain point in the game (supports might also play a role, not sure). Gaidens in Shadow Dragon on the other hand are highly critisized because they require killing over half your army to access. And the Gaidens themselves aren't all that interesting, just introducing a bunch of new characters of variable quality. If you take the access requirements out, they're not bad so to speak, but I feel like it's wasted potential. Archanea's cast is very underdeveloped compared to other games in the series, so from the start I've always thought it's Gaidens should have been side character focused like we eventually got in Three Houses. Why add more characters to the already large cast when we have a tonne of characters that are already unexplored? I think the worst offender of this is Hardin. He's a major character in the sequel to Shadow Dragon, yet he's barely noteworty in this game at all.
So, if the design of Shadow Dragon were to change so Gaidens were entirely focused on the existing side characters, what Gaidens would you like to see? Which characters do you think would be best to focus on, what would the story be behind the Gaidens and when would they happen?