Yes, miniforts require supply. I only occasionally use that strategy on 7/7 on X-maps. In particular I sometimes cannot colonize one of the central systems of (one of the offshoots of) an X map with a CSG, and I need to prevent the buildup in order for my fleets to be able to get anything done in the other wings, since this is early on, patrols will be drawn to the system, gravity guardians will ruin my day... I set up miniforts, snipers, spiders, riot starships, missile turrets, and occasionally a single regular fortress. This is more of a maintenance free deathtrap for a patrol that has already been crippled, however. Since I leave the AI up, I don't end up bottlenecking the patrol somewhere I need to go, a serious concern on X-maps.
What I have been doing frequently is I've often been colonizing the system NEXT to an ARS I absolutely want to hack (dealing with spireling and spire hammer, some of the choices I'd usually enjoy are absolutely worthless), and setting up a similar deathtrap, but this isn't nearly as abusive, as I need to invest significantly into turrets. Fire Control might have a significant effect on the viability of extreme knowledge and ship design hacking however.