For long time Aikido practitioners, it is can be difficult to discern what is a ‘beginner’s class’ and an ‘advanced’ class. Since most of the techniques we do, looks pretty much the same from the day we started training. Unlike other martial arts, where there are advanced katas, or even a special ‘elite’ group within a school that trains more intensively or exclusively for competition.
As far as I know, I haven’t heard of something like this in Aikido, as Aikido predominantly doesn’t encourage competition.
What is prevalent is this ‘advanced’ class segment, and what do we learn?

Same same, but Different
I’m not sure about other schools but for us, we are still looking at doing the same thing, irimi nage, shiho nage, the 5 Principles/ Teachings (一教 to 五教), and the usual stuffs.
The only difference is the movement, our tai sabaki is different, at different levels of proficiency, and years of practice, it will be smoother, more familiar and we are more confident with our positioning and placement. As with conditioning and muscle memory, it gets easier doing these moves day in, day out.
Herein lies the difficulty, when a beginner join us, we are not too particular with the specifics, as long as a shiho nage, looks vaguely like a shiho nage, it will be passable, and beginners are not conscious about ma-ai, stiff and uncomfortable with the movement, proximity and all that. So we would not want to overload a beginner’s sensory experience during the formative years in Aikido.
A similar example will be one of sword forging, a swordsmith will hammer a block of iron, and form the basic shape of the sword, constantly banging and banging until a crude shape of sword starts to emerge. Also removing any excess parts, constantly shaping and shaping.

Good Habits, Bad Habits
As we progress, habits are formed, some bad, some good, but without being too critical, we know what a good clean technique looks like and we work towards a high standards to executing a shiho-nage.
So in an ‘advanced’ class, we are looking to fine tune our technique, get rid of anything extra. like a small steps we take, or an extra back step, the hands might not be optimally rotated. Hips not squared nor centred.
Personally, I don’t prefer the word ‘advanced; Aikidoka, as it robs us of our focus on the beginner’s mind. Advance can distracts us from the reality that we are simply just beginning to discover our own body in relation to the waza. Advance might be a lie that we are closer to perfection, where we are much further from the truth. ‘Long time practicing Aikidoka’ sounds like a mouthful but it works for me.

‘Advanced’ Techniques
Of course you’ll see on social media, dynamic and dramatic high falls, and hip throws, fast and fluid movements in Aikido demonstrations. The reality is these folks trained very long and hard on the basic techniques, there is nothing additional in these techniques. There is no secret to how it is done. These techniques look amazing because these Aikidoka continuously polish themselves, ruthlessly removing any extra steps, deleting self doubts, cancelling out unnecessary movements and filtered down to the pure essence of body movement. They don’t move for the sake of moving, nothing is extra, everything is necessary.
Back to the swordsmith example, once the basic shape is hammered out, the sharpening and polishing begins, and the swordsmith might put the blade through many many rounds of fine grinding and minute sanding to get that shine and sharpness.
Also once the sword is made, and sharpen, it will need a regular level of attention to re-sharpen, for continuous use, fine minute adjustment here and there, regular maintenance of the entire sword, but essentially the structure is already made, it’s just the daily fine tuning here and there.
Aikido in the advance years of learning is the same, in the formative years you build the rough cut of a waza, then as you progress, you’ll make micro adjustments here and there, as you become dissatisfied with your movement, and realised that certain position is not optimal, or your uke exposes a critical flaw in your technique.

Self correct
Similarly, I implore our long time aikidokas to look at themselves to reflect, self correct, and check themselves. An honest and sincere uke is an external instrument to help us keeping ourselves grounded, ensure that we are constantly practicing, polishing and never settles for the fallacy of expert, nor perfection. There is always room for improvements, we just need to clear our clutter.