There are many in the karate world who will tell you that there are no hidden applications. Unfortunately, there are many in the karate world who will teach you bogus applications and take your money too. What's the average know-nothing karate guy or gal going to do? Let me break it down for you.
If you believe kata is open to free interpretation, and depends on your mood and circumstances, you have wasted your time. You should have been taking up boxing and looking up at cloud formations for inspiration; with boxing, at least you'd be able to punch out anyone who disparages your musings on cloud formations. For the poor karate guy who goes to the school where bunkai is up to you, read on. Performing kata, no matter how many times, will get you no closer to learning applications than the first day you put on a white belt. You've heard, perhaps, insanity defined as repeating the same mistakes and expecting different results. It's crazy to believe some new self-defense application will come to you in the nick of time simply because you marched through the Pinan series for many years.
Don't despair. Unlike clouds, the marbling of beef, or melted cheese on toast, the forms in kata are not random. This needs repeating. The forms in kata are not random. Did you ever notice that certain movements in kata recur pattern like? Did you ever notice that these repeating movements appear not only in different kata, but in different styles of martial arts? No, I'm not just talking Goju-Ryu and Shotokan, but also Judo, Tai Chi, Kuntao Silat, Aikido, etc., etc. No hwaaay?! Way! Here's something to ponder: maybe the guru's telling you there are no hidden applications, only know one way of fighting, or only one martial art.
Let that thought marinate a while and consider the different ranges in a fight. There's long distance, about as far away as you can kick. There's middle distance, about an arm's length away. Finally, there's close distance, close enough to smell the coffee on your opponent's breath, close enough to drive your forehead into his nose. If you belong to the Shotokan school, or a popular derivative, Kyokushin, you are probably most familiar with long and middle distance fighting. Why? Because tournament rules say those are the only approved ways of fighting.
When all you have is a hammer. . .
everything looks like a nail. The same applies to karate folk who are conditioned to fight in the long and middle distances. To them, everything looks like a punch, kick or block, except for the things that don't. These get dumped into the mystery bin of free interpretation. Be wary of the things that don't look like punches, kicks or blocks: they are the most susceptible to faulty interpretation. You will spot faulty interpretation when sensei says with a straight face,"this spinning jump is for when your legs are attacked with a barge pole," or, "now turn and face attacker number three." If kata were meant to help you fight multiple attackers (not that they can't), or barge pole wielding assailants, kata would come with submachine gun applications.
If you want to understand kata, you must dispense with the tournament mentality and consider fighting as comprising long, middle, and especially close distance engagement. You know that mystery bin, I'll bet the funny stances and gestures can all be explained, better yet applied, in a close distance fight.
Next, on the language of kata.