Sun Style Martial Arts
The Taiji form takes between 7-12 minutes to perform it can take longer of course so this is a good thing to practise as it has everything inside, my teacher related to me though that when you only have time to do one thing it should be Pi Quan, as it is everywhere in the Sun Style.
The mother skills are the most important things here and if not a lot of time the martial dances are essential to hone your technique.
familiarity with weapons is essential but that can be achieved by doing Ammara, with any weapon not just sticks.
The essential things are the basic footwork and doing combinations, making the transitions smoothly, making sure you have good co ordination between hands and feet, shadow boxing essential here.
Hunyuan Chen Shi Xin Yi Taiji
Without a doubt the 24 step form contains all you need to improve with daily practise, this can do done in anything from 7-20 minutes depending on your time available, also the 12 step qigong is another thing you could supplement or just do stand alone if time limited.
Obviously there are a lot of exercises that will give you reward for the effort to do them, Master Feng Zhiqiang advocated standing in Wuji for 45 minutes a day, as well as doing form and qigong but in this modern world we don’t always have the luxury of training 7-8 hrs a day, we can practise before work or after, get up early, practise during lunch there are so many ways to get your training but you must enjoy it, the daily grind is the most important thing.