These tips are directed for those interested in Nibbāna, and doing 4-10 hours a day of sitting meditation every day, or as frequently as possible. In other words, you’re interested simply in learning the key health principles that will help make your body pliable and pain free, and not interested in the ultimate aims of those other disciplines in and of themselves.
The real heart of taiji is here (linked thread). I would say, if you find a good teacher, 6 months to 1 year of practice will give you enough of the fundamentals. The rest, like jhana, the success depends on how well you’re able to relax, no further classes can help you with that.
With yoga, I would say 3-6 months of classes should be enough to get the fundamentals, safety precautions.
With both yoga, taiji, qigong, if you take more classes to learn more “stuff”, most of it is superficial and irrelevant to passadhi-bojjhanga. A lot of what they say that sounds like important detail is just arbitrary posture fetishes that differ between lineages. Some details for safety are important, but by far most of the stuff taught is just for theatrics, aesthetics, and totally irrelevant to passadhi-bojjhanga.
I would say in general, with taiji you tend to have more of an audience that is older, with health problems (back pain, knee pain, etc), so a good teacher that can teach you how to relax, show you where you had no idea where you were tense, is really valuable.
Yoga classes, you have the problem with yoga babes, and narcissists doing yoga competitively, and in relation to passadhi-bojjhanga, the vast majority of hatha yoga yogis have no idea what real relaxation is (that can get you into jhana). They have some relaxation while doing postures, but in between postures, and outside the yoga class, they forget all about relaxation. This is where taiji, and passaddhi-bojjhanga is infinitely better. Someone who can do jhana in all four postures, can do “relax” in taiji all the time, it’s a whole different ball game (AN 8.63, AN 3.63).
I don’t mean to be disparaging of yoga, there are genuine spiritual seekers, some who can do 4 jhana quality of samadhi, with genuine attainments, but those spiritual qualities aren’t attributable to the gymnastics portion of yoga. But what you find in a typical yoga class, is kind of like mcmindfulness meditation training courses.
In my own practice, if I were to give a very rough rating of the relative importance of everything with proportionate time spent focusing on that activity, I’d say 90% 8aam (noble eightfold path) + 7sb (awakening factors), 10% yoga type stretching postures.
the heart of taiji quan is relaxing/passadhi-bojjhanga, so you have 100% overlap with 8aam, 7sb, jhana.
For taiji quan, if you learn something like 24 yang, 37 chen man ching, or even no forms and just the famous 8 pieces of brocade, 18 movement senior qigong (expanded from 8 pieces of brocade), that would be more than enough.
The most famous grandmasters, if you look at what they spend most of their time doing daily for their taiji pracctice, most of the time is spent in 4 jhana quality of samadhi doing really simple movement (static standing or sitting posture, or super simple qigong movement with standing or slow walking).