“The CrossFit program is designed for universal scalability making it the perfect application for any committed individual regardless of experience. We’ve used our same routines for elderly individuals with heart disease and cage fighters one month out from televised bouts. We scale load and intensity; we don’t change programs.” –www.crossfit.com
Ok “Mr. Crossfit,” let me get this straight.  You’re telling me that you will have an elite cage fighter (with tight hamstrings and lats, horrible pelvic tilt, and tight IT bands) do the same workouts as an elderly individual with heart disease, (a herniated L4-L5, patellar arthritis, and forward shoulders)? Anyone with ANY fitness knowledge would know that you are an idiot.
Exercise should NEVER be “generalized”. 
Think about why you work out.  What are your goals?  Maybe you want to lose 20 pounds for a class reunion?  Maybe you want to improve your balance and strength so you can continue to do daily activities as you age?  Maybe you are an athlete who needs to increase your agility, power, and size?  Each person should have a reason why he or she wants to work out.  And as a client, you deserve to have a program designed just for you
Once a client has a program, they should ask a lot of “why” questions.  “Why do you have me doing a lot of upper back exercises?” “Why are we starting out with body weight?” It’s very important that a client asks questions because a better understanding of a workout makes a more effective workout.  If a trainer explains to their client that they are doing a lot of upper back/shoulder exercises to correct their forward shoulder problem; they are doing body weight exercises to check for any muscular imbalances or a deviation, a client is more aware of how important form and posture is in order to progress towards their goals. 
After reading a couple of “WOD”s, I ask myself “What is the purpose of doing 30 snatches (WOD Isabel, www.crossfit.com), a very technical power lift that should be no more than 6 reps? (anaerobic threshold reached at 6) The correct form and speed of a snatch makes it by far, the hardest exercise to perfect.  They should only be taught in a one on one setting, focusing on the breakdown of each biomechanical movement, falling into a synchronized pattern.
 A power movement should never be used in an aerobic form due to the high impact of pressure from the weight on multiplanar joints (shoulder, hip).  So in other words, unless you want to separate your shoulder or tear up your rotator cuff, (aka, your “Supraspinatus-InfraspinatusTeres Minor-Subscapularis” muscles) don’t do more than 6 reps of a power movement.
 “Those athletes who train for function end up with better form than those who value form over function. This is one of the beautiful ironies of training.” –www.crossfit.com
SERIOUSLY??
Repetitive bad form= habitual bad form= nonessential pressure on unsupported joints=injury= job security for orthopedic surgeons and physical therapists. Need I say more?
A lot of times we get requests from clients to just “kick their butt”.  They want a hard workout.  Sure, no problem.  I can easily get you sweating profusely and crawling on the floor without having to run 800 meters 3 three times and do a hundred burpess for time.  Because what’s the purpose of running 800 meters three times and doing a hundred burpess? Will that specific workout get you closer to your goal? 
My point of this blog wasn’t to bash Crossfit, even though I would never recommend anyone to do it.  My point is that program design should never be generalized.  Every person is different.  They walk differently, run differently, sit differently, and stand differently.  In order for a person to continue to successfully progress, each must focus on strengthening their weaknesses. The human body is like a car; no matter how big of an engine you have in it, if you have a bent frame, you have a totaled, non-drivable car.
 
Kimberly Renoud & Matt Wirth, Emerge Fitness Training