Perfect form is a term that is used often in the fitness industry. It generally refers to weight training, and means to train your movement in the recommended form for that exercise in order to prevent injuries. This, in concept, is a great idea because it allows the trainee to train using heavy weights while lowering the risk of injuries.
The problem with this concept is that it limits the range of strength that you can possess. Training with imperfect form can help to develop your strength when applied to odd-angle movements or high impact sports that require a lot of mobility. It can aid the strength of your tendons, and perhaps improve your flexibility by improving the strength of your movement in unconventional angles.
Does this mean to enter a gym and start an anarchic revolution against perfect form? Does this mean to perform your deadlifts hunched over with one leg to improve odd-angle strength? No, the perfect form is employed for those kinds of weights to avoid potentially permanent injuries to your muscular system.
Yet, perfect form is not an injury-proof system. It trains your strength in a straight line, which can limit the all around strength of a muscle around a joint. This means that for impact sports, making a move as simple as a turn or spin can grant you a tendon or muscle tear because of the lack of complete strength around that joint.
So how should you train imperfect form? What better way to train odd-angles than to train with odd objects! Training using things like chains, your bodyweight, large rocks or Atlas stones, tires, or kettlebells (a very good tool for overall strength) helps to develop your strength beyond what conventional weight lifting and 'perfect form' can offer you.
Isometrics is also a great way to push past many downfalls of perfect form training by strengthening your connective tissues for more complete strength, and by pushing past the sticking points in your lifts.