I'd consider two general components (the devil will be in the details per usual, but for discussion purposes, I'm simplifying) in the ki/jin/internal strength that would come into play at basic levels with regard to being cautious. I'm going to speak from more of a Chinese-categorization approach (though by no means purist as I'd never claim any such lineage) rather than Tohei's Ki-Aikido model, even though I don't think they're necessarily mutually exclusive.
There's the jin as ground/gravity forces that you train the body to better convey as an expression of ki, which one approach might be building the frame, letting the mind direct those forces through the frame, then relying increasingly less on the frame to build the mind-directing forces skill. There are body conditioning aspects here but at least for a while, they tend to be of the "apply common sense" (i.e., don't try to do this against a ridiculous force load) while connecting the insides and relying less on local muscle groupings milieu. Definitely a combination of skill/strength/conditioning/coordination so without someone that knows how to do it, articulate it and transmit it - learning will be a challenge at best.
The the ki as breath/elasticity side of things has more dangers built into the practice, partially due to folks giving themselves health problems because of training things wrong or with the wrong idea. I'll speak even less about that here but that's probably where the things can go off course the worst from a self-harm perspective (as opposed to the more typical self-perception disorder perspective).
Anyways, thought I'd throw those nuggets into the discussion pot - I generally agree with most that you're better off just training according to the paradigm at your school as long as you feel that it's a good fit. Unlike others seemingly, I don't discourage folks from asking questions (or questioning what you're learning/training) --> There has to be a balance between "shut up and train" to "intelligently articulating what the hell it is you're doing". A danger of martial arts practice is the sometimes built-in "have faith and believe" motif is such that it can weed out the intelligent thinkers from a practice and leave the folks itching to belong without rocking the boat remaining to carry on a practice that requires some pretty robust analytic abilities (both from "how the heck do I train this in ME" let alone "how do I teach it"). As neither of those latter things will come from just doing reps