To me, technique is the most important factor in resistance training. I cannot stand to see someone perform an exercise incorrectly. It shows that they have not put in the time to understand how or why they are doing that exercise. The how is important, but the why means so much more. It’s great to have an extensive database of exercises but understanding their individual purpose will greatly increase the way one can use them. It is easy to see the big muscles they are hitting, but what about the secondaries and stabilizers? Will it affect the cardiovascular system? Will it have a positive effect on the exercises planned last/next? Should it be high intensity to cook the athlete or low intensity to allow recovery? These questions are made in the assumption that their form is correct; what if the form is off? Their using different muscles than planned. The CNS is working overtime because the body cannot track a path for the exercise and breaking a bad habit is more time consuming than building a good one.
The other issue is the risk of injury. Resistance training should make you more resilient not more fragile. If you are getting injured in training, you are doing something wrong. I know what some people are thinking. “Well if your actually going hard, you can get injured with proper technique. Of course, you’ll never get hurt if you always go light.” Bullshit. If you are at the point in your lifting career to where you feel comfortable maxing out regularly, then you should know how to fail like a pro. You should know how to set safety bars and grab a spotter or ditch the weight if necessary. I have watched a lot of lifting competitions and shy of the Crossfit Games, I have rarely seen an injury in the Professional Brackets.
With all the connectivity we have these days, it is easy to look up exercises and make sure you have correct form. It’s not the end of the world, it just shows that no one knows everything. Never be afraid to learn something new. If you still need help, find a qualified fitness professional to talk to and have them go over your form in person. If you are a fitness professional, you have zero excuse for not increasing your knowledge on everything that could benefit your clients. Never have a client do any exercise that you haven’t done a thousand times before. You should be more than happy to breakdown every exercise piece by piece and explain why you chose those exercises in that order and how it fits their goals/limitation.