Lad the cut and thrust if you are referring to swords is not natural at all ...for one thing swords can be very different in what they are designed for ie slashing ...thrusting or indeed fencing and use said effectively then it is taught and learned. Yes ok give most healthy fir people a sword and let them loose then yup damage will occur for sure but to effectively cut etc no that is taught young man.
As for your natural v trained fighter, again that is dependent on what his training is it is not carte blanche that a trained fighter will go direct or linear at all. Also it all depends on the situation and the surroundings and most importantly what you face or you perceive you face eg in you face a knife wielding drunk that staggering etc the approach may be different to that if you face a sober guy would looked in control of his faculties. So don't young man make to many assumptions.
Im aware, i was just bringing up that some people viewed some techniques as go to's for the untrained. There are cases of people having the completer opposite view of each other, its not a science. I just only recalled the sword saying the best. (the age old cut or thrust, which is better)
Also, i would extend how people fight without any formal training to what they have seen and experienced. A country/culture which has adopted a sabre would be more prone to cutting with various weapons as that's the best means of attack with one than a culture with a rapier. (there are cases of weapons with hindsight working betting by thrusting being used to cut and the reverse, i would argue if someone showed that cutting worked best for this weapon most people would adopt it and endorse it if it worked for them)
The modern analogy i can think of this is baseball. If you do it/watch it a lot when you pick up a weapon you will draw on baseball on how to use it as that's the only thing you can draw on, its the only thing remotely close to the action you will be taking. (this can apply to fiction and non fiction, the former would be less reliable results) Or maybe you use axes a lot so you treat most weapons like you would a axe.
Just to cover it, you would need training to use a sword (well enough) its not the most beginner or untrained friendly weapon in the world, just to get that out of the way.
Just de weaponize this, i can do weapon related things easier.
(Excuse the broken second and third paragraph i deleted it to rewrite it and its content is much more simplistic and lacking than the original version)
addendum: Not too sure if any of this was disputed, but never hurts to elaborate a point and provide examples.