In
this thread from 2015 there is some discussion about this subject.
I've made a quick reading of it.
TL;DR version (apologies in advance if I missed something).
Geoff suggested, inpired by Cities: Skylines, to apply the IC effect only to a maximum number of supply-connected population (say 500, so that once your empire has 501+ you need to build a new IC).
That is intended to mitigate the advantage of bigger empires (which, with just one IC gets full benefit from the building and helps them steamroll over smaller empires).
Most posters liked the idea, some where ambivalent but saw the potential. No one discarded the idea from start. Several alternatives were suggested. Overall, the main problem didn't seem to be fear of micromanagement but problematic UI for the alternatives based on number of planets or distance from building. In the end the thread lost attention without any conclusion.
flap suggested the maximum number of jumps from the IC (as The Silent One here). That increases the strategic importance of where you place IC instead of no-brainer "far from enemy/homeworld".
flap wrote:this would work if there was an easy way on the map to see which systems have a bonus, and which don't.
And that seemed to be the problem: hard to implement a nice UI for this, as
Vezzra and others pointed out.
MatGB commented that before that time IC were causing effect only on planets within 500 uu, and that it had the same problem: hard to see what is already affected by the IC and where will be needed a new IC, so it was changed to full-empire effect.
MatGB also asked about using number of planets instead of number of population (like max 10 planets per IC), but
Vezzra pointed out that would be aprox. as hard as showing the effects for number of jumps or radius.
Recalling my own experience from city simulators and strategy games with aura effects, a possible way to improve UI could be to add a new window where you can select any of the researched AoE buildings (IC, SG, etc., one entry on the windows for each type), and then the planet where that building is built and those under reach gets a distinctive effect (e.g. using coloured, turning rings around the planet/s, similar to those shown in the UI when a planet is selected; and maybe something to the connecting lanes if the criterion is number of hops). The actual planet/s containing the AoE building get a darker/lighter colour from the planets under effect. If more than one building of each type is possible, each one and its AoE will be visible at the same time in the map.
Vezzra said about the UI problematic:
Finally, to make things even more tricky, keep in mind that we are dealing with user customizable content here. We can't just hardcode a toggle that queries ICs and then highlights all systems influenced by them. We'd need to come up with UI elements and an implementation that can handle all kinds of buildings that provide a bonus (that may even vary dependend on various factors) only within a certain distance.
I don't know if what I've suggested above does clash with this.
em3 suggested, to reduce microing for the option of each IC affecting a max. number of planets that would be selectable, to let the computer automatically select the planets that maximise production (i.e. highest population industry-focused planets). Geoff pointed out that it could bring extra microing by forcing the player to search for the highest population planets to set to industry focus.