Eventually you will get an athlete that has developed some technical flaws. Some self-learned or possibly from a previous coach. Based on the nature of the flaw, correcting them can sometimes be challenging.
Technical flaws are like weeds. You can pull out the tops of the weeds and have the garden look great for a week… until the weeds grow back. Or you could pull out the root and never have to worry about the weeds growing back again.
It’s important to try to kill the biggest weed(s) first and to recognize that changing technique is a process. Determine which flaw, if corrected, will provide the biggest performance increase and start there. Expecting to change an athlete’s techniques in one or two sessions is shortsighted. Likewise, expecting to make more than one or two technique corrections in a given session is unrealistic. Trying to correct more than just one or two flaws in a session typically results in correcting none due to overload.
Cues are very important in this process. Try to limit cues to as few words as possible. Explaining torques, levers, extension/flexion, and angles will further confuse most athletes. A confused athlete makes for a slow athlete. A slow athlete that overthinks typically makes more mistakes. You can see how it can quickly become a vicious cycle.
There is no correlation with the amount of feedback given with how good of a coach you may be. In fact, there might be a negative correlation in some cases. Rather than focusing on the quantity of feedback, focus on the quality. Try to make your feedback meaningful and useful.
Treat the cause not the symptoms. You’ll end up banging your head against the wall if you go after the symptoms first.