I practice Wu style Taiji from a Wu Tu Nan lineage as well as Yu Xian Pai Neidan and between that and Zhan Zhuang… some days it’s hard to do both.
I have also noticed I have to space out the Taiji Qigong(from Wu Tu Nan) with some of the Neidan methods by several hours. And the Taiji I also have to watch out for certain hours of the day because it’s much more activating. So I would say it depends on the systems you are practicing.
Some methods mesh well together and can get a boost from other methods. While some other methods would directly conflict with each other and could cause you to go out of balance(into deviation). You’re better off gaining the experience with one system so you can manage your own state and Yin/Yang balance before incorporating other systems/methods.