I think this is an example of a thread that should contain a qualifying statement of which kind of players you want to answer. Like the "Civ4 lovers/Civ5 haters, thoughts on Civ6?" thread has great feedback because it specified particular respondents, then of course everyone was free to join the discussion, but it was a clear perspective to start the dialogue. Here, you should probably state what kind of game you are playing and the type of playstyle you want to hear back from... peaceful? domination?
With no qualifier, you get a range of responses from the SimCiv builder crowd (about half of the population on the forum in my experience) that will tell you they never build any encampments, maybe one or two multi-players that have their own specific needs that might not apply to 95% of the single players, and a few warmongers that are still around (that didn't quit after Civ4)... But without context of how someone plays, it's hard to put their feedback to use.
For example, I can tell you I build an encampment in every city, and I don't track stable v. barracks but probably more barracks since cheaper. But the only reason I build encampments is I'm a weirdo with my own self-imposed rule set -- I never build holy sites or theaters, and I max encampment improvements before building units. However, If this was not my rule set, I would probably not build them because they seem rather useless, and besides the horrid AI cannot engage in war so XP is useless. Promotions are just a fun side show, not necessary to walk over the pushover AI. But I like great generals so enjoy the points, and I like the small production from the additional buildings (altho the min/max crowd will break it down to armory never worth its cost), and I like placing it to act as a second city center for ranged defense.
And the real reason that I don't track stable v. barracks is simply because my old eyes cannot tell if a city has a barracks or a stable. (Cue someone telling me I'm stupid for not hovering my mouse somewhere or not being able to clearly see it and it's not the fault of the Civ6 UI...) Without any way to easily tell if the unit I'm about to build is in a barracks or stable city, and because the xp doesn't matter, why should I care which? My build rule is if that city has horses nearby (hey even I can see that on the UI!), I will build a stable in that city, so maybe later I will build a horsey there if I can see the horsies. If this wasn't true I guess I'd build a lot more stables because knights are overpowered -- but again who cares since you can pound on the useless AI with a slinger, warrior and a ball of string.