After trying to warp space, why not trying to warp time too?
In kata a very important concept is rhythm. Since they are the representation of a battle, each kata has its own rhythm: the sequence of moves does not flow at constant speed like a metronome, but each technique is given a proper timing depending on what it actually represents in terms of application to such imaginary battle. Hence there are both fast and slow techniques, and the pause between any two of them can be sometimes as short as possible and sometimes longer. Furthermore, the kata can be typically broken down in smaller subsequences, each of which could be done as a "burst" followed by a pause of a few seconds, standing firm in the last position.
While there is usually an "official" way to do each kata, and that also includes an official rhythm to use as reference, I've see experienced people (especially of black belt rank) choose different rhythms, probably because each person may have a slightly different interpretation of the battle in his imagination. Being still very much a beginner, interpreting things in my personal way is not really my concern yet... but once again, the purpose of these ideas is only to vary the challenges of training, so that while on one hand I focus on learning each kata in the correct way and through repetition iron the kinks and get used to do it without thinking, on the other hand I can occasionally break away from the repetition routine to force my concentration to work in a different way, as if "resetting" the whole learning process. Here are my first few ideas for doing that by changing the rhythm.
#1 - Kiai repositioning
Almost every kata, with few exceptions, features one or more "kiai"-shout at some point. These mark the most decisive and potentially encounter-ending strikes of the sequence, usually the ones done with the greatest power and possibly also speed.
However some of our teachers have already hinted at the idea of making our own decisions on which strikes we mean to be decisive. This does not normally allow to place the "kiai" somewhere else, at least in front of the class... but of course it can be tried when no one's watching.
So here is my first and simplest rhythmic variation idea: to experiment repositioning a kata's "kiai" shouts to a different technique than normally. This actually has effects on the rhythm of the techniques both before and after, such as anticipating or delaying a pause, or creating one when normally there isn't any.
You can find a confirmation that this idea is not completely off from the two basic Gekisai kata in Goju-Ryu style, which are very similar to each other: these two kata have in common a sequence of five techniques on a fixed Zenkutsudachi stance, but while the first kata (Gekisai dai Ichi) has the "kiai" on the 5th technique, the second kata (Gekisai dai Ni) has it on the 3rd technique instead.
#2 - Forced rhythm
Once we have understood the correct rhythm for a kata, a possible challenge is to force the kata into a different rhythm, even if this might be potentially incorrect in the sense that it may fail to represent a reasonable application of its techniques.
It can be as simple as choosing the same forced rhythm for each subsequence, for example "one technique slow, pause, two techniques quick, pause", and stick to this pattern even when the correct way would imply the pauses in different places.
If something more challenging is wanted, the forced rhythm can be applied to the whole sequence rather than "resetting" it at each new subsequence, even if this means that those subsequences cease to be separate. Does this idea sound wrong? If it does, it's because it is... but this is kind of the whole point: doing it with a wrong rhythm is what challenges our ability to take a step back from the "automatic" performance of a kata, and exercise more control over each technique.
#3 - Zeroed rhythm
As a special case of the previous idea, we can try to perform the kata with a completely "flat" rhythm, meaning that every move in the sequence is done with equal speed and timing, with pauses of the same length.
Clearly, this removes a lot of meaning from the kata, and should definitely be done really only once in a while in our practice. But if you try to do this on a kata you know well and have been doing for such a long time that it has become automatic for you, you'll see for yourself how challenging it can actually be when you arrive at a pause point and instead you have to go straight into the next move without delay, even if you're doing all of this slowly!
#4 - Speed dialling
The last idea is about a more "soft forcing" approach: rather than changing the time relationship between techniques each of which is still done at correct speed, we now keep those relationships intact but we increase or decrease the speed of each technique individually.
Personally I've noticed that this actually requires me even a greater concentration effort than all the previous ideas. Perhaps the best approach to make this work, is first of all to recall clearly which techniques are normally slow and which ones are fast. Second, perform the kata start-to-end (at reduced speed overall, using longer pauses) and purposefully slow down all the fast techniques, as slow or even slower than the normally slow ones. Finally, try to speed up (as gradually as necessary) the normally slow techniques while keeping the rest slow. Ideally the final result would be an odd version of the kata where all that was normally slow is now fast and all that was normally fast is now slow. Enjoy!