Hmm yeah Shunka Ayami is definitely a counter example, she's top idol, always exclusive contract girl, always making solo works, never as unnamed fake amateur. Especially, always holding the top 1,2 or 3 spot for which ever studio signing her. And keeping her same name when transferring. But Tsumbomi is difficult to classify as planning idol. She is old by JAV standard, and seems to make quite a few mild fetish vids, so that's on the yes side. I'm not too familiar with her career, just going over her last 30 or so vid covers... She mostly make solo works with top studios like MIDE and WANZ. So That's a NO.
Basically making a non-planning vid involves: start with a commercially hot idol, get one or more (forgettable) studs, have a camera guy, a guy for lighting and sound and go. Oh you might want a theme or idea, but there are already 30ish well established themes (e.g. female home tutor) so just pick a random one.
Then a planning vid starts with a slightly more outlandish theme (e.g. group of MILFs go on hotspring vacation and sexual R&R) then you have to find a location, prefer multiple different rooms for each scene, plan out some scenes (intro, girls A,B,C,D suck stud S, then B fucks S, then A&D paizuri S, then C&B fuck S, then A,B,C,D with S short scene and outtro), write a script (could be just minor rewrite of a stock script), may be get a vehicle, maybe 2 or even more camera guys, then finally you say... now we need 4 idols. By this point the main criteria maybe isn't how hot or successful the idols are, but whoever is available (fitting schedule of so many moving parts) and don't repeat the same girls from last 3 vids in the same series.
You noticed yourself planning vid is rather vague concept, but at least that's a tag the industry is using consistently. But planning idol is doubly vague. Roughly I'd say a planning idol makes a lot of multi-idol vids (number of actresses >= 4), make vids for many studios, often as unnamed fake amateur. Basically a status that the idol herself wouldn't be proud of.