I was however making decent progress at learning an instrument at the time (the French horn, if you must know) and thought there should be some sort of tool to learn the fundamentals of first-person video game shooting using time honored music practice techniques.
The key to getting really killer music technique is to go as smoothly and calmly as possible, over and over again, even if that means going at a fraction of the target speed.
I would have liked to see an fps trainer that lets you practice shots at anywhere from 1/5th to 1x game speed, so you could master it at very slow speeds and gradually up the "tempo".
(There are some very good trainer programs now in AD 2024, but none that I know of that let you manipulate speed like that.)