Why not 6 times immediately? Why not simply until you find a lead that sends you elsewhere?
Oh, that's simple actually! It's a perfect reflection of what's going on 'under the hood'.
It's not "reading ahead" to the next MysteryStage to see if it is the same but for the number of times needed to Investigate and, if so, combining the result.
e: And I am considering doing that, yeah, along with other potential hint measures. Still trying to find the precise target/tone for 'how much of an investigation game is this and/or how optional are the thinking/puzzly bits'
Btw. I hope/expect you add branching mysteries where some leads may also be dead ends, etc.
Those are in presently, actually! It's just not realistically/easily achieved to get the other ending for FITM atm. (Not sure if it functions properly just yet but the structure supports it [stuff like manual flags and so on are to-be-added so I can more directly control/predict outcomes from player choices made during the mystery])
Endings can also open/close available Mysteries, too, so I can make 'divergent paths' which alter the city and so on. This'll be important as 'A New Sensation' for instance should permanently add Redqueens and Greykings to the encounters you can face inside The City unless/until you run into a mystery which allows for their removal (and also introduce the new dungeon of 'Thorne Manor' from the sequel mystery to Flowers in the Mist (would be unlocked from getting Ending A/0).