Depends on the unit: I do recall keeping +5 HP on some of them, but others it just seemed like a waste (esp when many long range enemies like fliers have significantly better speed than my squishies), so I used the spots for other things.
I do I think I understand the gist of your strategy, and I've played around with it myself at the start of the game (having every unit wield a ranged weapon of some kind). It's just that it...didn't seem especially effective for me, mostly because of the experience required to get there. It seemed like I was just better off giving people javalins or throwing axes or whatever, as that required far less time investment and it seemed like a smarter use of time developing skills they excelled at. I believe I'm also familiar with what everything you stated (I believe I've referenced everything you mentioned in previous posts, albeit with the name confusion for the bow skills). The problem is that with unit interests/weaknesses, I just simply haven't found time to push for getting everyone into either a magic/bow class at some point, letting them develop skills to move to the next class, and then promoting them to higher classes where they can actually wield weapons that are strong enough to be effective to any degree. Just as a comparison point, I've had Leonie learning armor since basically the start of the timeskip when I realized I wanted to make her into a Great Knight. I assigned her to learning armor (exclusively for most of the time, so a 1.5 multiplier) and had her boosting armor learning skills with group tasks...and 8 chapters later, she's just now finally hitting B rank. B rank is where most of the quality spells/silver bows unlock, which seems to kind of be the bare minimum for doing significant damage in later maps. Maybe combat just boosts it by a crazy degree, I have difficulty imagining it being substantial enough of a boost to overtake group tasks by enough of a margin that it would be a worthwhile investment of time.
I'm also aware of the combat arts, but I've largely done my best to avoid relying on them too heavily since, well, they chew through weapons really quickly. Also being limited to one attack for most of the arts means that they haven't been especially useful to me either most of the time since moving one space closer generally isn't that much more harmful and you can often get a double from it.
That being said, it's good to hear something like this, because it may very well be that the game has balancing issues designed around teams that are very heavily ranged focus. Perhaps it just requires a heavier investment at the beginning that I simply didn't put the time into because it didn't seem like it would pay off well. My team isn't really set up to test something like that now, so I can't vouch for how good or bad it is. But it's helpful to keep in mind, and hopefully something I can go back through and test on a later playthrough.
EDIT: I also want to say, I'm not putting any of this out there to bash Awakening/Fates. I thoroughly enjoyed both games (as my banner probably indicates), and Awakening would probably be in my top 10 all time. I'm also not going to necessarily disagree with you that this game is inherently easier than Awakening w/o grinding, I just haven't found it to be as easy as you've said. But, again, different experiences.
No worries, I wouldn't even mind if that was your intention, I'm well used to Awakening/Fates bashing haha. If you do another playthrough you should try embracing the range meta, not just to prove a point of course. I can't deny there's fun in just walking up and killing everyone, that's why I still enjoy the gameplay lul.
Focusing on one weapon will get it more experience than two at once, but not significantly so. My units have all promoted in a timely manner still, but I did have to burn through more advanced and master seals than I probably would have if I didn't spread experience. Then again, all Master Classes require multiple weapon ranks so it probably is best to split.
Bows weigh less, have higher might and more utility than hand axe/javelins/etc. I can confirm that they're worth the investment even for non archer classes. E rank Iron+ is still my go to general purpose weapon, not just for Bows but most weapon types as it has the best accuracy and good weight n dmg. For magic, I've mostly used the basic spells like Fire n Wind again for their high accuracy and low weight, but it's not just dmg magic, Warp and Rescue are super OP. I will pull out the Brave Bows and Ragnaroks when needed of course.
Apart from Curved Shot, Point Blank Volley, and Hunter's Volley (while I had Snipers), I don't use Combat Arts too often for the same reasons, though I don't mind burning uses on iron n training tier weapons as they're cheap enough to repair. Unlike Awakening/Fates, it seems all enemies that aren't dedicated archers or mages are 1 range locked, so yeah 2 range is enough to outrange most foes. Still good to have that utility when you need it. It can be the difference between reaching an enemy, hitting an enemy, avoiding their counterattack, and/or staying out of range of other enemys as you attack.
Btw, you were saying Chapter 19 was a particularly challenging map with compact enemy groups earlier. I had a slightly different experience, one that ended in 3 turns. xD
Only one of the things I mentioned requires a DLC item. The rest are all options in the normal game, and options you don't really have to grind for. And there's plenty more you could through out there like vengence/nosferatu, free streetpass skills, debuff weapons, broken weapons the royals have etc, but it seems that you don't want to actually consider any of these factors. I guess you could choose to never pair your units or anything. By the same logic you could choose to never use ranged weapons.
So yeah, if you use the best options in three houses and don't take advantage of any of the good options in fates or awakening, then they're much harder than three houses. You care about facts and evidence... but just ignore any that go against you.
But I do take advantage of those good options, I've said this already. I always play trying to find the strongest strategys, not just in Three Houses but all games. Guess I shoulda made that more clear, but naturally when discussing a game's difficulty it makes more sense to assume the player is playing optimally rather than purposely sabotaging themselves, so it should go without saying that when I compare to Awakening/Fates I am taking into account their OP stuff. As powerful as Galeforce and Replicate are, I'd argue the range meta is moreso. Certainly more relevant as in 3 Houses every unit can take advantage from the very beginning of the game compared to promoted Lv.15 skills you can't get until mid-lategame, nor on every unit unless you grind excessively. I will say Awakening probably isn't that much more thought inducing, been a long while since I played it, but Fates surely is.