@Ramiel You're bit wrong. In mid game when early resource shortages are gone, I build almost all districts right after colonization. It's not really admin efficient, but I have jobs for ages. Buildings can't be built from day one though. You need some pops. With IP/genocidal/Gestalt problem is slightly alleviated by extra build slot from Adaptability. And it's not as bad with Authoritarians either, since you can resettle. For Egalitarians it's quite different and natural growth is the only way to get pops, beside raiding and slave market.
When you get your planets to their natural pop limit, things get nasty. You can stop growth as gestalts, but it's waste of resources, namely pops. Slavers can resettle. Fine, but look at original post: having 50+ planets with ~40-50 pops in nead of resettlement every year, just to avoid trouble, and you can't do it automatically, like 'click a button to resettle unemployed pops from other planets up to the job limit'. No, you need to open resettlement tab for every single planet, scroll and choose a planet to resettle from, scroll down to unemployed pops and click them several times, while counting, just not to get to many extra pops on your target planet, since your amenities/housing can be low. Think of colonization of L-cluster, with 10+ plus planets at once.
If economy is solid and the build is optimized for influence generation, Habitats can be created almost overnight, or at least every second year. Even if you play tall, number of colonized celestial bodies grow very fast.
Take egalitarians and things are getting nasty. You need basic mineral income and in many cases food from your planets, so they are best to be used with plenty of resource districts. In such case housing is again a problem at some point. Unemployed homeless pops even at Utopian abundance cause trouble, both crime and stability issues. You can slow down growth, but it costs influence for decisions and cause unhappiness.
Prior to 2.2 unemployed as well as employed pops would migrate ad libitum, filling in your new territories. Now it's just a number, and quite few unemployed pops will be staying till things get too bad for natural pop decline.
All things built, planets at 80+ pop limit is when this game turns into micromanagement hell. Strategy? Which strategy when you simply do tedious tasks again and again, plus game turn into crawl itself. Very, very enjoyable.