1) Becoming Addicted To Short-Term Benefits
The biggest issue with these mobility exercises that everyone is doing these days is that they are being widely performed with no long-term plan in mind. Individuals at the fitness clubs are working on regaining the same degrees of range of motion before every single workout. If you're spending this much time on gaining those degrees of range, then you should absolutely be doing the subsequent work to make sure it stays! Otherwise, you're simply bailing the boat without plugging the hole, so to speak.
This brings us to our next fact:
2) Freeing Up Ranges That You Aren't Strengthening In
How do you maintain range of motion once you free it up? You strengthen and stabilize the soft-tissue around it by training IN that range. It blows my mind when I see people at the gym spending 20 minutes working on their overhead shoulder flexion, yet they're only pushing half-reps on the shoulder press.
I can't wait to never do an overhead press!
Not bothering to do the necessary work to strengthen those ranges of motion, at best, means that that range is never going to stick and stay available to you. At worst, you're going to hurt yourself. Which leads us to...
3) Freeing Up Too Much Range Too Soon
Going back to the stabilization point, if you don't strengthen within a range, that range is useless to you. On the same train of thought, if you mobilize a joint too aggressively and your range drastically increase, there's a risk even if you do try to strengthen there; that risk being that if there's not enough existing stability already, then the joint may fail you if you try to lift too heavy or stress the joint into that range. Think of that joint as a Jenga tower. If you're removing blocks to increase its movement, you need to reinforce and balance it out to prevent collapse.
And at the same time have hours of family fun!
4) You're Mobilizing Past The Limits Of The Joint
Another problem we run into is when people are trying to mobilize into ranges that aren't even supposed to be mobile. My favourite example is when I see individuals using those bands to stretch their shoulders behind them into extension.
Taking this photo actually made my shoulder sore, but I did it for you!
News flash: You don't do any activities or exercises in that excessive range (except for those ones that you should probably be avoiding anyway). Furthermore, your joints do not appreciate being pulled that far.
At points such as this, we've completely stopped gliding the joint along its surfaces or stretching the muscle tissue. By this time, all that you're doing is stretching the ligaments. Last time I checked, you don't want to stretch your ligaments.
5) You're Trying To Mobilize When Mobility Isn't The Problem
You have trouble getting into a deep squat, so let's mobilize those hips into flexion! Right?
So often, I see people thinking that they're lacking the ability for their joint to fully glide, and so they waste time trying to increase those ranges. But wait, can you pull you're knee into your chest? If so, then the joint can glide just fine. If anything, you probably have a problem with muscular spasm and tension.
So, before grabbing that band, take a moment to assess where the problem is actually coming from.
6) Not Understanding How Joints Move
Lastly, once you've completely determined that, yes, you have an actual joint restriction, that you will definitely strengthen in the increased range, that you won't stress your ligaments, and you have a long-term stability plan in mind, let's mobilize that joint!
But let's mobilize it properly, mmkay?
My best example of this is one that I see constantly: the hip extension stretch with the band pulling back on the hip.
Here's the thing, which I will so artfully articulate in my MS Paint diagram here. When the limb goes in one direction, the joint surface that is moving does not necessarily go the same way.
This example is quite easy to visualize. When the hip flexes forward, the head of the femur moves back in the opposite direction. Oh-so coincidentally, the direction that the femoral head moves is the opposite way that people seem to enjoy pulling on it with their bands. Counterproductive, as you can see. Here's the right way to be doing that exercise.
These same principles apply to every other joint. Unfortunately, not every joint glides in an as-easy-to-picture fashion. So please, if you're going to force a joint surface in a specific direction, please do your research correctly or speak to a professional.
Band mobility definitely has it's place in certain rehab and training plans. It's a temporary measure only, however, as the subsequent training should involve strengthening to stabilize that newly-acquired range so that it sticks around. Know the joint that you're trying to mobilize, understand the joint's limits so that you don't unnecessarily stress them, and only increase the range if you require/intend to use it.