I'm not convinced that we should credit either of the scientists with a "plan". They aren't master criminals or anything: they are just mad scientists who want to do their thing and not to be disturbed by the outside world that is incapable of understanding their greatness and the benevolence of their work.
Adams is credited with curing criminals and other insane people for the benefit of the UFP, and that's what he keeps doing till the bitter end. He just loses perspective when the only patients remaining are virtual incurables destined for Elba II, and can only be treated by application of the most questionable methods. His attempt to deal with the disruption caused by Kirk's arrival and disapproval of Adams' work is improvised on what he near-successfully did to van Gelder. For all we know, he planned on treating Kirk much the same way and again pleading "accident" or "self-inflicted damage" - which would be in keeping with the facts, as Kirk did self-inflict on his own free will, out of a desire that Adams could plausibly label as "misguided" after the damage was done.
What Adams didn't count on was his lack of time, due to Spock being suspicious already thanks to the unanticipated revelations from the mind meld...
As for Korby, he was even more surprised than Adams, but his improvisation had even sounder basis: he knew he could make a fully convincing duplicate Kirk. If he wanted, he might have had this Kirk commit an error that would destroy the Enterprise
and guarantee Korby continued peace, perhaps for another decade or so considering how low Starfleet seems to be on starship resources. But his "plan" need not have extended quite that far.
Korby is IMHO the less interesting (even if more sympathetic) misguided/immoral genius in that his hand is being forced by Ruk, sometimes almost literally so. Adams is merely tangled in a web of his own making, and thus is a more "self-contained" and perhaps "fuller" dramatic element. But both have a long history of working almost alone, with "people" of questionable moral sense (insane criminals or alien androids) their only companions, which explains much of their antics.
As for the episodes in general, I sort of prefer the creepiness of "Girls" over the more straightforward classic asylum entertainment of "Dagger". Sure, creepy aliens are an easy way to create threat, conflict and tension, and the shortcomings of man in dealing with man are psychologically more interesting, but something is lacking from the pacing of the latter half of "Dagger" in the dramatic tension department. Or perhaps it's just the moodier lighting and more intricate set design of "Girls"...