Yes, that topic is covered by Grossman in the book; On Killing.
SLA Marshal a high ranking US Army officer did in depth research about combat troops & how they conduct missions.
It puts a lot of topics into perspective re: military training, legal issues(UCMJ, treaties, rule of land warfare etc).
In many cases, real front line troops fired guns or killed enemy troops because they did not want to be looked at as cowards or to viewed as unreliable.
It's worth noting too, that due to extended DoD/service member study-R&D, the rates of fire in combat went from approx 15-20% to approx 90-95%(combat units in SE Asia, 1962-1975 era) over many years.
Training & conditioning(mindset, motivation) assisted greatly with these service members.
Grossman's writings about the types of kills; mechanical, distance & personal makes a lot of sense. It's a Oprah "aaa-hah" moment
. Personal kills seem the most stressful & the root cause of the most mental health issues for the obvious reasons. It was interesting to read how the USMC combat veteran(SE Asia conflict) described Marines who would cut or cause injury to their own hands, when doing a sentry elimination method in low light.
Blood, gore, injury, trama, etc are all a direct part of personal kills.