I've always considered that there must be a negative side effect to studying occlumency beyond its difficulty.
Perhaps as a person increases their mental barriers, they become less (naturally) outwardly emotional, appearing less human? Or more introspective as they review their life, causing significant pain or changing who they are in the process? Perhaps the ability to spend more time in the mindscape than in real time causes weird side effects?
Time in the mindscape frequently exceeds that spent outside, which I find somewhat annoying. I'm of the opinion that it should be decoupled from reality, sometimes fast and sometimes slow, with the speed somewhat unpredictable but related to the specific mental activity at hand.
Frequently fanfiction writers use a mindscape as an analog for mental defenses, which though somewhat farfetched, is an adequate way of representing what is occurring to the reader.
That said, how are actions in the mindscape remembered? If one is organizing and editing their memories, do they remember this process? Do they retain memories of their organizing process, which memories must then also be organized? Perhaps it's turtles all the way down.