Is it a good idea to be switching out my party?

[Altus]

I just hit the second timeskip after Gerrard's reign and I noticed one of my retinue members not doing much damage. I've been switching out my party with theme and enemy weaknesses in mind. Should I just stick to a few people?

[Chester]

Both approaches are valid, though I would encourage you to continually switch up your party - you'll be recruiting a lot of new classes as the game progresses, some of which are strong in areas your initial party isn't, so being flexible opens up more options. Also, I think it's more fun.

As for why a party member isn't doing much damage, there's a few things to look at. Is their weapon aligned with their stats (bows/shortswords work off of Dex, not Strength)? Do they have weapon rank in what they're using? Is the enemy weak/resistant to weapon type? Is their class more focused on support or general coverage than pure damage? Or maybe they're just starting to fall behind your new recruits. For example, Light Infantry can cover a lot of different damage types to give you more coverage, but they'll likely lag behind in damage to someone more focused on one or two weapon types. If it looks like better/newer/more interesting units have become available, don't be afraid to swap them out (even mid-generation if you'd like) and try something new.

[Chester]

(You may already be aware of this, but you don't have to keep using a unit for them to become strong/developed. Their strengths are based on two things, their stats and their weapon ranks. Unless you equip them with gear to boost it, their stats won't change at any point in the game - there's some variation within a class through the generations, but each class has a general range they will fall in. For example, Heavy Infantry has strength between 15-18, while Male Mercenaries have strength between 18-21. Weapon Ranks are based on your Universal Weapon Ranks, which you can see in the Imperial Standing tab. Basically, the more you use a weapon/magic type, the more it universally grows. Each class has a rank based on these stats - Rangers, for example, will have their bow rank boosted by the Universal Bow Rank, while most Mages generally won't get any bonus from that. So if you've been ignoring a unit all game, but been developing the weapon/magic that it uses, it will still be developing throughout your playthrough.)